Methods and applications of non-planar imaging arrays

ABSTRACT

System, devices and methods are presented that provide an imaging array fabrication process method, comprising fabricating an array of semiconductor imaging elements, interconnecting the elements with stretchable interconnections, and transfer printing the array with a pre-strained elastomeric stamp to a secondary non-planar surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the following U.S. ProvisionalApplications, each of which is incorporated herein by reference in itsentirety: U.S. Provisional Patent Application having Ser. No. 61/144,149filed Jan. 12, 2009 entitled “Non-planar imaging arrays”; and UnitedStates Provisional Patent Application having Ser. No. 61/156,906 filedMar. 16, 2009 entitled “Curved imaging array”.

This application is a continuation-in-part of copending U.S.Nonprovisional patent application having Ser. No. 12/636,071 filed Dec.11, 2009 entitled “Systems, Methods, and Devices Using StretchableElectronics for Medical Applications”, which is incorporated herein byreference in its entirety. U.S. Nonprovisional patent application havingSer. No. 12/636,071 claims priority to the following U.S. ProvisionalApplications: Ser. No. 61/121,568 entitled “Endoscopy Device” filed Dec.11, 2008; Ser. No. 61/121,541 entitled “Nerve Bundle Prosthesis” filedDec. 11, 2008; and Ser. No. 61/140,169 entitled “Body Tissue Screener”filed Dec. 23, 2008, the entirety of each of which is incorporatedherein by reference. Further, U.S. Nonprovisional patent applicationhaving Ser. No. 12/636,071 is a continuation-in-part of and claims thebenefit of copending U.S. Nonprovisional patent application Ser. No.12/616,922 entitled “Extremely Stretchable Electronics” filed Nov. 12,2009, the entirety of which is incorporated herein by reference.Nonprovisional patent application Ser. No. 12/616,922 claims the benefitof U.S. Provisional Application No. 61/113,622 entitled “ExtremelyStretchable Interconnects” filed on Nov. 12, 2008, the entirety of whichis incorporated herein by reference. Also, Nonprovisional patentapplication Ser. No. 12/616,922 is a continuation-in-part of, and claimsthe benefit of copending U.S. Non-Provisional application Ser. No.12/575,008, entitled “Catheter Balloon Having Stretchable IntegratedCircuitry and Sensor Array” filed on Oct. 7, 2009, the entirety of whichis incorporated herein by reference. Nonprovisional Application No.12/575,008 claims priority to U.S. Provisional Application No.61/103,361 entitled “Catheter Balloon Sensor and Imaging Arrays”, filedOct. 7, 2008, the entirety of which is incorporated herein by reference;and U.S. Provisional Application No. 61/113,007 entitled “CatheterBalloon with Sensor and Imaging Array”, filed Nov. 10, 2008 the entiretyof which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to systems, apparatuses, and methodsutilizing expandable or stretchable integrated circuitry and sensorarrays on expandable, flexible or stretchable substrates in or onnon-planar imaging arrays.

BACKGROUND OF THE INVENTION

For the purpose of this invention we may consider two types of opticalimaging systems: planar and non-planar electronic systems. There aremany advantages to using non-planar image sensor arrays including widefield of view, low aberrations and reduced complexity of the systems.However, the majority of available optical imaging systems used todayare planar due to restrictions imposed by current techniques used forfabricating optoelectronic systems. Existing technologies are to a largeextent geared toward the production of rigid devices on flat surfaces.The resulting systems do not have the ability to absorb strains asrequired for non-planar designs.

In order to achieve non-planar optoelectronic systems one may processdevices directly onto curved surfaces or alternatively onto flatsurfaces which are then deformed into the desired shape. Both methodshave been actively researched in the past decade with varying degrees ofsuccess.

Alternative routes to creating curved focal plane arrays includetemplate generation by ion beam proximity lithography and relieftransfer by step and flash imprint lithography; large-scale,heterogeneous integration of nanowire arrays by contact printing; andsoft lithographic printing of amorphous silicon on curved substrates.The above-mentioned techniques suffer from limitations with multilevelregistration of circuit layers and use of low performance materialswhich struggle to compete with single crystalline silicon devicescurrently in use.

Other relevant methods include wet chemical thinning of silicon wafersto produce curved silicon substrates for subsequent processing; andmicro-structuring of monolithic silicon die using a deep reactive ionetch on SOI wafers. The prior is not compatible with currentsemiconductor fabrication processes and the latter is undeveloped due tothe plethora of manufacturing challenges. Therefore a need exists forviable routes for production of curved imaging arrays with theutilization of conventional planar processing technology and subsequentdeformation to produce different shapes of imaging arrays.

SUMMARY OF THE INVENTION

The present invention pertains to the field of imaging, morespecifically the production of curved imaging arrays and its integrationinto camera modules. These camera modules may be integrated directlyinto a number of applications for image capture and video recording suchas camera phones, web cams, compact camera systems, and the like.

Embodiments of the invention pertain specifically to Complementary MetalOxide Semiconductor (CMOS) imagers, though one skilled in the art willrecognize that Charge-Coupled Device (CCD) imagers can be created in asimilar manner. The imaging arrays may be fabricated in hemispherical,ellipsoid, parabolic and other non planar shapes. Methods for creatingthe above mentioned imaging arrays are described.

The advantages of having a curved imaging array have been known for along time within the field of optics. The present invention allows themanufacture of cameras with few lenses. This new degree of freedom willfurther enable the push toward smaller and more discrete imaging deviceswhile reducing the total cost of systems with expensive composite lenscomponents. Fewer lenses results in less reflection and diffractiondefects in images. Therefore there is the added benefit of reduceddistortion and aberration. Additionally, a curved image sensor reducessystem and pixel vignetting by increasing the amount of light enteringthe sensor and the decreasing the angle of incidence of light enteringeach pixel. One more important aspect of the curved imager is itsability to significantly increase the field of view of images beingrecorded.

The invention described herein, avoids the problems of multilevelregistration mentioned in the prior art by providing a method whichemploys conventional semiconductor processing techniques and tools witha high degree of precision. It also overcomes the persistent problem ofmost flexible/stretchable electronic device by using high performancesingle crystal silicon for applications that necessitate reliability andsuperior functionality under strain in complex geometries.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully apparent from the followingdescription and appended claims, taken in conjunction with theaccompanying figures. Understanding that these figures merely depictexemplary embodiments of the present invention they are, therefore, notto be considered limiting of its scope. It will be readily appreciatedthat the components of the present invention, as generally described andillustrated in the figures herein, could be arranged and designed in awide variety of different configurations. Nonetheless, the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying figures in which:

FIG. 1 is a schematic depiction of embodiments of the invention;

FIG. 2 depicts a buckled interconnection;

FIGS. 3A-E depict a stretchable electronics configuration withsemiconductor; islands mounted on an elastomeric substrate withstretchable interconnects;

FIG. 4 depicts an extremely stretchable interconnect;

FIG. 5 depicts a raised stretchable interconnect with expandableelastomeric substrate;

FIGS. 6A-F depict a method for controlled adhesion on an elastomericstamp;

FIGS. 7A-K illustrates the process of creating an image sensor viastretch processing;

FIG. 8 is an illustration of a CMOS active pixel;

FIG. 9 is an illustration of a second CMOS active pixel;

FIG. 10 is an illustration of an interconnected pixel array with onepixel per island;

FIGS. 11-13 are illustrations of an interconnected pixel array with 4pixels per island;

FIG. 14 is an illustration of the typical architecture of a CMOS imager;

FIGS. 15A-B depict an illustration of the backside illumination concept;

FIGS. 16A-H outlines a method for transfer printing of “stretchprocessed” imaging arrays onto the curved surface of a BGA and thesubsequent steps required to fabricate a BGA packaged curved imagesensor;

FIGS. 17-20 outlines a method for fabricating curved backsideilluminated imagers from stretch processed image sensors anincorporating it into a BGA package;

FIGS. 21A-F is a summary of the process shown in FIGS. 17-20;

FIGS. 22A-E illustrates a process of creating a backside illuminatedimager with no color filter or micro-lens;

FIGS. 23A-F illustrates a second method for creating a backsideilluminated imager with no color filter or lens;

FIGS. 24A-F illustrates a method for creating a planar backsideilluminated image sensor;

FIGS. 25A-B illustrates a method for creating a camera module using acurved imaging array;

FIG. 26 depicts an embodiment for a stretchable interconnect non-planarelectronic structure;

FIG. 27 depicts an embodiment for a stretchable non-planar electronicimaging device fabrication process using interconnected islands ofsemiconductor elements;

FIG. 28 depicts an embodiment for a single-pixel non-planar electronicimaging array with stretchable interconnects;

FIG. 29 depicts an embodiment for a multiple-pixel non-planar electronicimaging array with stretchable interconnects;

FIG. 30 depicts an embodiment for a stretchable non-planar electronicimaging device for replacement of a planar electronic imaging device;

FIG. 31 depicts an embodiment for a stretchable non-planar electronicimaging structure whose surface is altered by mechanical actuation;

FIG. 32 depicts an embodiment for a stretchable non-planar electronicimaging device fabrication process using transfer printing;

FIG. 33 depicts an embodiment for a planar electronic back-sideillumination imaging device fabrication process using transfer printing;

FIG. 34 depicts a process for assembling curvilinear circuitry accordingto an embodiment of the invention;

FIGS. 34A and 34B depicts the process for applying a curvilinear arrayof circuitry to an endoscopic device according to an embodiment of theinvention; and

FIG. 35 depicts an embodiment of an endoscopic device according to thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Detailed embodiments of the present invention are disclosed herein;however, it is to be understood that the disclosed embodiments aremerely exemplary of the invention, which can be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure. Further, the terms and phrases usedherein are not intended to be limiting but rather to provide anunderstandable description of the invention.

The terms “a” or “an,” as used herein, are defined as one or more thanone. The term “another,” as used herein, is defined as at least a secondor more. The terms “including” and/or “having” as used herein, aredefined as comprising (i.e., open transition). The term “coupled” or“operatively coupled,” as used herein, is defined as connected, althoughnot necessarily directly and not necessarily mechanically or physically.“Electronic communication” is the state of being able to convey orotherwise transmit data either through a physical connection, wirelessconnection, or combinations thereof.

As described herein, the present invention comprises devices, systems,and methods utilizing flexible and/or stretchable electronic circuits onflexible, expandable, or inflatable surfaces. With reference to thepresent invention, the term “stretchable”, and roots and derivationsthereof, when used to modify circuitry or components thereof describescircuitry and/or components thereof having soft or elastic propertiescapable of being made longer or wider without tearing or breaking, andit is also meant to encompass circuitry having components (whether ornot the components themselves are individually stretchable as statedabove) that are configured in such a way so as to accommodate astretchable, inflatable, or expandable surface and remain functionalwhen applied to a stretchable, inflatable, or otherwise expandablesurface that is stretched, inflated, or otherwise expanded respectively.The term “expandable”, and roots and derivations thereof, when used tomodify circuitry or components thereof is also meant to have the meaningascribed above. Thus, “stretch” and “expand”, and all derivationsthereof, may be used interchangeably when referring to the presentinvention. The term “flexible”, and roots and derivations thereof, whenused to modify circuitry or components thereof describes circuitryand/or components thereof capable of bending without breaking, and it isalso meant to encompass circuitry having components (whether or not thecomponents themselves are individually flexible as stated above) thatare configured in such a way so as to accommodate a flexible surface andremain functional when applied to a flexible surface that is flexed orotherwise bent. In embodiments, at the low end of ‘stretchable’, thismay translate into material strains greater than 0.5% withoutfracturing, and at the high end to structures that may stretch 100,000%without a degradation of electrical performance. “Bendable” and rootsand derivations thereof, when used to modify circuitry or componentsthereof describes circuitry and/or components thereof able to be shaped(at least in part) into a curve or angle, and may sometimes be usedsynonymously herein with “flexible”.

FIG. 1 is a schematic depiction of embodiments of the invention. Furtherdescription of each of the components of FIG. 1 will be includedthroughout the specification. Circuitry 1000S is applied, secured, orotherwise affixed to substrate 200. In embodiments, substrate 200 isstretchable and or expandable as described herein. As such the substrate200 can be made of a plastic material or can be made of an elastomericmaterial, or combinations thereof. Note that the term “plastic” mayrefer to any synthetic or naturally occurring material or combination ofmaterials that can be molded or shaped, generally when heated, andhardened into a desired shape. The term “elastomer” may refer anaturally occurring material or a synthetic material, and also to apolymeric material which can be stretched or deformed and return to itsoriginal shape without substantial permanent deformation. Suchelastomers may withstand substantial elastic deformations. Examples ofelastomers used in substrate material include polymeric organosiliconcompounds (commonly referred to as “silicones”) includingPolydimethylsiloxane (PDMS).

Other materials suitable for the substrate include polyimide;photopatternable silicone; SU8 polymer; PDS polydustrene; parylene andits derivatives and copolymers (parylene-N); ultrahigh molecular weightpolyethylene; poly ether ether ketones (PEEK); polyurethanes (PTGElasthane®, Dow Pellethane®); polylactic acid; polyglycolic acid;polymer composites (PTG Purisil Al®, PTG Bionate®, PTG Carbosil);silicones/siloxanes (RTV 615®, Sylgard 184®); polytetrafluoroethylene(PTFE, Teflon®); polyamic acid; polymethyl acrylate; stainless steel;titanium and its alloys; platinum and its alloys; and gold. Inembodiments, the substrate is made of a stretchable or flexiblebiocompatible material having properties which may allow for certaindevices to be left in a living organism (referred to as the human body2000) for a period of time without having to be retrieved.

Some of the materials mentioned above, specifically parylene and itsderivatives and copolymers (parylene-N); ultrahigh molecular weightpolyethylene; poly ether ether ketones (PEEK); polyurethanes (PTGElasthane®, Dow Pellethane®); polylactic acid; polyglycolic acid;polymer composites (PTG Purisil Al®, PTG Bionate®, PTG Carbosil);silicones/siloxanes (RTV 615®, Sylgard 184®); polytetrafluoroethylene(PTFE, Teflon®); polyamic acid; polymethyl acrylate; stainless steel;titanium and its alloys; platinum and its alloys; and gold, arebiocompatible. Coatings for the substrate to increase itsbiocompatibility may include, PTFE, polylactic acid, polyglycolic acid,and poly(lactic-co-glycolic acid).

The materials disclosed for substrate 200 herein may be understood toapply to any of the embodiments disclosed herein that require substrate.It should also be noted that materials can be chosen based on theirproperties which include degree of stiffness, degree of flexibility,degree of elasticity, or such properties related to the material'selastic moduli including Young's modulus, tensile modulus, bulk modulus,shear modulus, etc., and or their biodegradability.

The substrate 200 can be one of any possible number of shapes orconfigurations. In embodiments, the substrate 200 is substantially flatand in some embodiments configured to be a sheet or strip. Yet it shouldbe noted that such flat configurations of substrate 200 can be anynumber of geometric shapes. Other embodiments of flat substrates will bedescribed below including substrates having a tape-like or sheetconfiguration. Flexible and/or stretchable substrate 200 having a sheetor otherwise substantially flat configuration may be configured suchthat substrate 200 can be folded, furled, bunched, wrapped or otherwisecontained. In embodiments, a substrate 200 configured as such can befolded, furled, bunched, collapsed (such as in an umbrella-likeconfiguration), wrapped, or otherwise contained during delivery throughnarrow passageways in the subject's body 2000 and then deployed into anunfolded, unfurled, etc. state once in position for deployment.

In embodiments where the substrate 200 is stretchable, circuitry 1000Sis configured in the applicable manners described herein to bestretchable and/or to accommodate such stretching of the substrate 200.Similarly, in embodiments where the substrate 200 is flexible, but notnecessarily stretchable, circuitry 1000S is configured in the applicablemanners described herein to be flexible and/or accommodate such flexingof the substrate 200. Circuitry 1000S can be applied and/or configuredusing applicable techniques described below, including those describedin connection with exemplary embodiments.

As mentioned above, the present invention may employ one or more of aplurality of flexible and/or stretchable electronics technologies in theimplementation thereof. Traditionally, electronics have been fabricatedon rigid structures, such as on integrated circuits, hybrid integratedcircuits, flexible printed circuit boards, and on printed circuitboards. Integrated circuits, also referred to as ICs, microcircuits,microchips, silicon chips, or simple chips, have been traditionallyfabricated on a thin substrate of semiconductor material, and have beenconstrained to rigid substrates mainly due to the high temperaturesrequired in the step of inorganic semiconductor deposition. Hybridintegrated circuits and printed circuit boards have been the main methodfor integrating multiple ICs together, such as through mounting the ICsonto a ceramic, epoxy resin, or other rigid non-conducting surface.These interconnecting surfaces have traditionally been rigid in order toensure that the electrical interconnection methods, such as solderjoints to the board and metal traces across the boards, do not break orfracture when flexed. In addition, the ICs themselves may fracture ifflexed. Thus, the field of electronics has been largely constrained torigid electronics structures, which then tend to constrain electronicsapplications that may require flexibility and or stretchabilitynecessary for the embodiments disclosed herein.

Advancements in flexible and bendable electronics technologies haveemerged that enable flexible electronics applications, such as withorganic and inorganic semiconductors on flexible plastic substrates, andother technologies described herein. Further, stretchable electronicstechnologies have emerged that enable applications that require theelectronics to be stretchable, such as through the use of mounting ICson flexible substrates and interconnected through some method ofstretchable electrical interconnect, and other technologies as describedherein. The present invention may utilize one or more of these flexible,bendable, stretchable, and like technologies, in applications thatrequire the electronics to operate in configurations that may not be, orremain, rigid and planar, such as applications that require electronicsto flex, bend, expand, stretch and the like.

In embodiments, the circuitry of the invention may be made in part or infull by utilizing the techniques and processes described below. Notethat the below description of the various ways to achieve stretchableand/or flexible electronics is not meant to be limiting, and encompassessuitable variants and or modifications within the ambit of one skilledin the art. As such, this application will refer to the following UnitedStates Patents and Patent Applications, each of which is incorporated byreference herein in its entirety: U.S. Pat. No. 7,557,367 entitled“Stretchable Semiconductor Elements and Stretchable ElectricalCircuits”, issued Jul. 7, 2009 (the “'367 patent”); U.S. Pat. No.7,521,292 entitled “Stretchable Form of Single Crystal Silicon for HighPerformance Electronics on Rubber Substrates”, issued Apr. 29, 2009 (the“'292 patent”); United States Published Patent Application No.20080157235 entitled “Controlled Buckling Structures in SemiconductorInterconnects and Nan membranes for Stretchable Electronics”, filed Sep.6, 2007 (the “'235 application”); United States Patent Applicationhaving Ser. No. 12/398,811 entitled “Stretchable and FoldableElectronics”, filed Mar. 5, 2009 (the “'811 application”); United StatesPublished Patent Application No. 20040192082 entitled “Stretchable andElastic Interconnects” filed Mar. 28, 2003(the “'082 application”);United States Published Patent Application No. 20070134849 entitled“Method For Embedding Dies”, filed Nov. 21, 2006 (the “'849application”); United States Published Patent Application No.20080064125 entitled “Extendable Connector and Network, filed Sep. 12,2007 (the “'125 application”); United States Provisional PatentApplication having Ser. No. 61/240,262 (the “'262 application”)“Stretchable Electronics”, filed Sep. 7, 2009; United States PatentApplication having Ser. No. 12/616,922 entitled “Extremely StretchableElectronics”, filed Nov. 12, 2009 (the “'922 application”); UnitedStates Provisional Patent Application having Ser. No. 61/120,904entitled “Transfer Printing”, filed Dec. 9, 2008 (the “'904application”); United States Published Patent Application No.20060286488 entitled “Methods and Devices for FabricatingThree-Dimensional Nanoscale Structures”, filed Dec. 1, 2004; U.S. Pat.No. 7,195,733 entitled “Composite Patterning Devices for SoftLithography” issued Mar. 27, 2007; United States Published PatentApplication No. 20090199960 entitled “Pattern Transfer Printing byKinetic Control of Adhesion to an Elastomeric Stamp” filed Jun. 9, 2006;United States Published Patent Application. No. 20070032089 entitled“Printable Semiconductor Structures and Related Methods of Making andAssembling” filed Jun. 1, 2006; United States Published PatentApplication No. 20080108171 entitled “Release Strategies for MakingTransferable Semiconductor Structures, Devices and Device Components”filed Sep. 20, 2007; and United States Published Patent Application No.20080055581 entitled “Devices and Methods for Pattern Generation by InkLithography”, filed Feb. 16, 2007.

“Electronic device” is used broadly herein to encompass an integratedcircuit(s) having a wide range of functionality. In embodiments, theelectronic devices may be devices laid out in a device islandarrangement, as described herein including in connection to exemplaryembodiments. The devices can be, or their functionality can include,integrated circuits, processors, controllers, microprocessors, diodes,capacitors, power storage elements, antennae, ASICs, sensors, imageelements (e.g. CMOS, CCD imaging elements), amplifiers, A/D and D/Aconverters, associated differential amplifiers, buffers,microprocessors, optical collectors, transducer includingelectromechanical transducers, piezo-electric actuators, light emittingelectronics which include LEDs, logic, memory, clock, and transistorsincluding active matrix switching transistors, and combinations thereof.The purpose and advantage of using standard ICs (in embodiments, CMOS,on single crystal silicon) is to have and use high quality, highperformance, and high functioning circuit components that are alsoalready commonly mass-produced with well known processes, and whichprovide a range of functionality and generation of data far superior tothat produced by a passive means. Components within electronic devicesor devices are described herein, and include those components describedabove. A component can be one or more of any of the electronic devicesdescribed above and/or may include a photodiode, LED, TUFT, electrode,semiconductor, other light-collecting/detecting components, transistor,contact pad capable of contacting a device component, thin-film devices,circuit elements, control elements, microprocessors, interconnects,contact pads, capacitors, resistors, inductors, memory element, powerstorage element, antenna, logic element, buffer and/or other passive oractive components. A device component may be connected to one or morecontact pads as known in the art, such as metal evaporation, wirebonding, application of solids or conductive pastes, and the like.

Components incapable of controlling current by means of anotherelectrical signal are called passive devices. Resistors, capacitors,inductors, transformers, and diodes are all considered passive devices

For purposes of the invention, an active device is any type of circuitcomponent with the ability to electrically control electron flow. Activedevices include, but are not limited to, vacuum tubes, transistors,amplifiers, logic gates, integrated circuits, semiconducting sensors andimage elements, silicon-controlled rectifiers (SCRs), and triode foralternating current (TRIACs).

“Ultrathin” refers to devices of thin geometries that exhibitflexibility.

“Functional layer” refers to a device layer that imparts somefunctionality to the device. For example, the functional layer may be athin film, such as a semiconductor layer. Alternatively, the functionallayer may comprise multiple layers, such as multiple semiconductorlayers separated by support layers. The functional layer may comprise aplurality of patterned elements, such as interconnects running betweendevice-receiving pads.

Semiconductor materials which may be used to make circuits may includeamorphous silicon, polycrystalline silicon, single crystal silicon,conductive oxides, carbon annotates and organic materials.

In some embodiments of the invention, semiconductors are printed ontoflexible plastic substrates, creating bendable macro-electronic,micro-electronic, and/or nano-electronic devices. Such bendable thinfilm electronics devices on plastic may exhibit field effect performancesimilar to or exceeding that of thin film electronics devices fabricatedby conventional high temperature processing methods. In addition, theseflexible semiconductor on plastic structures may provide bendableelectronic devices compatible with efficient high throughput processingon large areas of flexible substrates at lower temperatures, such asroom temperature processing on plastic substrates. This technology mayprovide dry transfer contact printing techniques that are capable ofassembling bendable thin film electronics devices by depositing a rangeof high quality semiconductors, including single crystal Si ribbons,GaAs, INP wires, and carbon nano-tubes onto plastic substrates. Thishigh performance printed circuitry on flexible substrates enables anelectronics structure that has wide ranging applications. The '367patent and associated disclosure illustrates an example set of steps forfabricating a bendable thin film electronics device in this manner. (SeeFIG. 26A of the '367 patent for Example).

In addition to being able to fabricate semiconductor structures onplastic, it has been demonstrated that metal-semiconductor electronicsdevices may be formed with printable wire arrays, such as GaAsmicro-wires, on the plastic substrate. Similarly, other high qualitysemiconductor materials have been shown to transfer onto plasticsubstrates, including Si nano-wires, micro-ribbons, platelets, and thelike. In addition, transfer printing techniques using elastomeric stampsmay be employed. The '367 patent provides an example illustration of themajor steps for fabricating, on flexible plastic substrates, electronicsdevices that use arrays of single wires (in this instance GaAs wires)with epitaxial channel layers, and integrated holmic contacts. (See FIG.41 of the '367 patent). In an example, a semi-insulating GaAs wafer mayprovide the source material for generating the micro-wires. Each wiremay have multiple ohmic stripes separated by a gap that defines thechannel length of the resultant electronic device. Contacting a flat,elastomeric stamp of PDMS to the wires forms a van der Waals bond. Thisinteraction enables removal of all the wires from the wafer to thesurface of the PDMS when the stamp is peeled back. The PDMS stamp withthe wires is then placed against an uncured plastic sheet. After curing,peeling off the PDMS stamp leaves the wires with exposed ohmic stripesembedded on the surface of the plastic substrate. Further processing onthe plastic substrate may define electrodes that connect the ohmicstripes to form the source, drain, and gate electrodes of theelectronics devices. The resultant arrays are mechanically flexible dueto the bendability of the plastic substrate and the wires.

In embodiments, and in general, stretchable electronics may incorporateelectrodes, such as connected to a multiplexing chip and dataacquisition system. In an example, an electrode may be fabricated,designed, transferred, and encapsulated. In an embodiment, thefabrication may utilize and/or include an SI wafer; spin coating anadhesion layer (e.g. an HMDS adhesion layer); spin coating (e.g. PMMA)patterned by shadow mask, such as in oxygen RIE; spin coating Polyimide;depositing PECVD SiO2; spin 1813 Resist, photolithography patterning;metal evaporation (e.g. Ti, Pt, Au, and the like, or combination of theaforementioned); gold etchant, liftoff in hot acetone; spin Polyimide;PECVD SiO2; spin 1813 Resist, photolithography patterning; RIE etch, andthe like. In this embodiment, the fabrication step may be complete withthe electrodes on the Si wafer. In embodiments, the Si wafer may then bebathed in a hot acetone bath, such as at 100 C for approximately onehour to release adhesion layer while PI posts keep electrode adhered tothe surface of the Si wafer. In embodiments, electrodes may be designedin a plurality of shapes and distributed in a plurality of distributionpatterns. Electrodes may be interconnected to electronics, multiplexingelectronics, interface electronics, a communications facility, interfaceconnections, and the like including any of the facilities/elementsdescribed on connection with FIG. 1 and/or the exemplary embodimentsherein. In embodiments, the electrodes may be transferred from the Siwafer to a transfer stamp, such as a PDMS stamp, where the material ofthe transfer stamp may be fully cured, partially cured, and the like.For example, a partially cured PDMS sheet may be ˜350 nm, where the PDMSwas spun on at 300 rpm for 60s, cured 65 C for 25 min, and used to liftelectrodes off of the PDMS sheet. In addition, the electrodes may beencapsulated, such as wherein the electrodes are sandwiched between asupporting PDMS layer and second PDMS layer while at least one of thePDMS layers is partially cured.

In embodiments, stretchable electronics configurations may incorporateflex PCB design elements, such as flex print, chip flip configurations(such as bonded onto the PCB), and the like, for connections toelectrodes and/or devices, and for connections to interface electronics,such as to a data acquisition system (DAQ). For example, a flex PCB maybe joined to electrodes by an anisotropic conductive film (ACF)connection, solder joints may connect flex PCB to the data acquisitionsystem via conductive wires, and the like. In embodiments, theelectrodes may be connected onto a surface by employing apartially-cured elastomer (e.g. PDMS) as an adhesive.

In embodiments, stretchable electronics may be formed into sheets ofstretchable electronics. In embodiments, stretchable sheets may be thin,such as approximately 100 μm. Optionally, amplification and multiplexingmay be implemented without substantially heating the contact area, suchas with micro-fluidic cooling.

In embodiments, a sheet having arrays of electronic devices comprisingelectrodes may be cut into different shapes and remain functional, suchas through communicating electrode islands which determine the shape ofthe electrode sheet. Electrodes are laid out in a device islandarrangement (as described herein) and may contain active circuitrydesigned to communicate with each other via inter-island stretchableinterconnects so that processing facility (described herein) in thecircuitry can determine in real-time the identity and location of othersuch islands. In this way, if one island becomes defective, the islandscan still send out coordinated, multiplexed data from the remainingarray. Such functionality allows for such arrays to be cut and shapedbased on the size constraints of the application. A sheet, and thuscircuitry, may be cut to side and the circuitry will poll remainingelectrodes and/or devices to determine which are left and will modifythe calibration accordingly. An example of a stretchable electronicssheet containing this functionality, may include electrode geometry,such as a 20×20 array of platinum electrodes on 1 mm pitch for a totalarea of 20×20 mm²; an electrode impedance, such as 5 kohm at 1 khz(adjustable); a configuration in a flexible sheet, such as with a 50 μmtotal thickness, and polyimide encapsulated; a sampling rate, such as 2kHz per channel; a voltage dynamic range, such as +/−6 mV; a dc voltageoffset range, such as −2.5 to 5 V, with dc rejection; a voltage noise,such as 0.002 mV, a maximum signal-to-noise ratio, such as 3000; aleakage current, such as 0.3 μA typical, 10 μA maximum, as meets IECstandards, and the like; an operating voltage of 5 V; an operating powerper channel, such as less than 2 mW (adjustable); a number of interfacewires, such as for power, ground, low impedance ground, data lines, andthe like; a voltage gain, such as 150; a mechanical bend radius, such as1 mm; a local heating capability, such as heating local tissue by up to1° C.; biocompatibility duration, such as 2 weeks; active electronics,such as a differential amplifier, a multiplexer (e.g. 1000 transistorsper channel); a data acquisition system, such as with a 16 bit A/Dconverter with a 500 kHz sampling rate, less than 2 μV noise, data loginand real-time screen display; safety compliance, such as to IEC10601;and the like.

In embodiments of the invention, mechanical flexibility may represent animportant characteristic of devices, such as on plastic substrates, formany applications. Micro/nano-wires with integrated ohmic contactsprovide a unique type of material for high performance devices that canbe built directly on a wide range of device substrates. Alternatively,other materials may be used to connect electrical components together,such as connecting electrically and/or mechanically by thin polymerbridges with or without metal interconnects lines.

In embodiments, an encapsulation layer may be utilized. An encapsulatinglayer may refer to coating of the device, or a portion of the device. Inembodiments, the encapsulation layer may have a modulus that isinhomogeneous and/or that spatially varies. Encapsulation layers mayprovide mechanical protection, device isolation, and the like. Theselayers may have a significant benefit to stretchable electronics. Forexample, low modulus PDMS structures may increase the range ofstretchability significantly (described at length in the '811application). The encapsulation layer may also be used as a passivationlater on top of devices for the protection or electrical isolation. Inembodiments, the use of low modulus strain isolation layers may allowintegration of high performance electronics. The devices may have anencapsulation layer to provide mechanical protection and protectionagainst the environment. The use of encapsulation layers may have asignificant impact at high strain. Encapsulants with low moduli mayprovide the greatest flexibility and therefore the greatest levels ofstretchability. As referred to in the '811 application, low modulusformulations of PDMS may increase the range of stretchability at leastfrom 60%. Encapsulation layers may also relieve strains and stresses onthe electronic device, such as on a functional layer of the device thatis vulnerable to strain induced failure. In embodiments, a layering ofmaterials with different moduli may be used. In embodiments, theselayers may be a polymer, an elastomer, and the like. In embodiments, anencapsulation may serve to create a biocompatible interface between animplanted stretchable electronic system, such as Silk encapsulation ofelectronic devices in contact with tissue.

Returning to flexible and stretchable electronics technologies that maybe utilized in the present invention, it has been shown that buckled andwavy ribbons of semiconductor, such as GaAs or Silicon, may befabricated as part of electronics on elastomeric substrates.Semiconductor ribbons, such as with thicknesses in the submicron rangeand well-defined, ‘wavy’ and/or ‘buckled’ geometries have beendemonstrated. The resulting structures, on the surface of, or embeddedin, the elastomeric substrate, have been shown to exhibit reversiblestretchability and compressibility to strains greater than 10%. Byintegrating ohmic contacts on these structured GaAs ribbons,high-performance stretchable electronic devices may be achieved. The'292 patent illustrates steps for fabricating stretchable GaAs ribbonson an elastomeric substrate made of PDMS, where the ribbons aregenerated from a high-quality bulk wafer of GaAs with multiple epitaxiallayers (See FIG. 22). The wafer with released GaAs ribbons is contactedto the surface of a pre-stretched PDMS, with the ribbons aligned alongthe direction of stretching. Peeling the PDMS from the mother wafertransfers all the ribbons to the surface of the PDMS. Relaxing theprestrain in the PDMS leads to the formation of large scale buckles/wavystructures along the ribbons. The geometry of the ribbons may depend onthe prestrain applied to the stamp, the interaction between the PDMS andribbons, and the flexural rigidity of the ribbons, and the like. Inembodiments, buckles and waves may be included in a single ribbon alongits length, due for example, to thickness variations associated withdevice structures. In practical applications, it might be useful toencapsulate the ribbons and devices in a way that maintains theirstretchability. The semiconductor ribbons on an elastomeric substratemay be used to fabricate high-performance electronic devices, buckledand wavy ribbons of semiconductor multilayer stacks and devicesexhibiting significant compressibility/stretchability. In embodiments,the present invention may utilize a fabrication process for producing anarray of devices utilizing semiconductor ribbons, such as an array ofCMOS inverters with stretchable, wavy interconnects. Also, a strategy oftop layer encapsulation may be used to isolate circuitry from strain,thereby avoiding cracking.

In embodiments, a neutral mechanical plane (NMP) in a multilayer stackmay define the position where the strains are zero. For instance, thedifferent layers may include a support layer, a functional layer, aneutral mechanical surface adjusting layer, an encapsulation layer witha resultant neutral mechanical surface such as coincident with thefunctional layer, and the like. In embodiments, the functional layer mayinclude flexible or elastic device regions and rigid island regions. Inembodiments, an NMP may be realized in any application of thestretchable electronics as utilized in the present invention.

In embodiments, semiconductor ribbons (also, micro-ribbons,nano-ribbons, and the like) may be used to implement integratedcircuitry, electrical interconnectivity between electrical/electroniccomponents, and even for mechanical support as a part of anelectrical/electronic system. As such, semiconductor ribbons may beutilized in a great variety of ways in the configuration/fabrication offlexible and stretchable electronics, such as being used for theelectronics or interconnection portion of an assembly leading to aflexible and/or stretchable electronics, as an interconnected array ofribbons forming a flexible and/or stretchable electronics on a flexiblesubstrate, and the like. For example, nano-ribbons may be used to form aflexible array of electronics on a plastic substrate. The array mayrepresent an array of electrode-electronics cells, where thenano-ribbons are pre-fabricated, and then laid down and interconnectedthrough metallization and encapsulation layers. Note that the finalstructure of this configuration may be similar to electronic devicearrays as fabricated directly on the plastic, as described herein, butwith the higher electronics integration density enabled with thesemiconductor ribbons. In addition, this configuration may includeencapsulation layers and fabrication steps which may isolate thestructure from a wet environment. This example is not meant to limit theuse of semiconductor ribbons in any way, as they may be used in a greatvariety of applications associated with flexibility and stretchability.For example, the cells of this array may be instead connected by wires,bent interconnections, be mounted on an elastomeric substrate, and thelike, in order to improve the flexibility and/or stretchability of thecircuitry.

Wavy semiconductor interconnects is only one form of a broader class offlexible and stretchable interconnects that may (in some cases) bereferred to as ‘bent’ interconnects, where the material may besemiconductor, metal, or other conductive material, formed in ribbons,bands, wire, traces, and the like. A bent configuration may refer to astructure having a curved shape resulting from the application of aforce, such as having one or more folded regions. These bentinterconnections may be formed in a variety of ways, and in embodiments,where the interconnect material is placed on an elastomeric substratethat has been pre-strained, and the bend form created when the strain isreleased. In embodiments, the pre-strain may be pre-stretched orpre-compressed, provided in one, two, or three axes, providedhomogeneously or heterogeneously, and the like. The wavy patterns may beformed along pre-strained wavy patterns, may form as ‘pop-up’ bridges,may be used with other electrical components mounted on the elastomer,or transfer printed to another structure. Alternately, instead ofgenerating a ‘pop-up’ or buckled components via force or strainapplication to an elastomeric substrate, a stretchable and bendableinterconnect may be made by application of a component material to areceiving surface. Bent configurations may be constructed frommicro-wires, such as transferred onto a substrate, or by fabricatingwavy interconnect patterns either in conjunction with electronicscomponents, such as on an elastomeric substrate.

Semiconductor nanoribbons, as described herein, may utilize the methodof forming wavy ‘bent’ interconnections through the use of forming thebent interconnection on a pre-strained elastomeric substrate, and thistechnique may be applied to a plurality of different materials. Anothergeneral class of wavy interconnects may utilize controlled buckling ofthe interconnection material. In this case, a bonding material may beapplied in a selected pattern so that there are bonded regions that willremain in physical contact with the substrate (after deformation) andother regions that will not. The pre-strained substrate is removed fromthe wafer substrate, and upon relaxation of the substrate, the unboundedinterconnects buckle (‘pop-up’) in the unbonded (or weakly bonded)regions. Accordingly, buckled interconnects impart stretchability to thestructure without breaking electrical contact between components,thereby providing flexibility and/or stretchability. FIG. 2 shows asimplified diagram showing a buckled interconnection 204S between twocomponents 202S and 208S.

In embodiments, any, all, or combinations of each of the interconnectionschemes described herein may be applied to make an electronics supportstructure more flexible or bendable, such as applying bent interconnectsto a flexible substrate, such as plastic or elastomeric substrates.However, these bent interconnect structures may provide for asubstantially more expandable or stretchable configuration in anothergeneral class of stretchable electronic structures, where rigidsemiconductor islands are mounted on an elastomeric substrate andinterconnected with one of the plurality of bent interconnecttechnologies. This technology is presented here, and also in the '262application, which has been incorporated by reference in its entirety.This configuration also uses the neutral mechanical plane designs, asdescribed herein, to reduce the strain on rigid components encapsulatedwithin the system. These component devices may be thinned to thethickness corresponding to the desired application or they may beincorporated exactly as they are obtained. Devices may then beinterconnected electronically and encapsulated to protect them from theenvironment and enhance flexibility and stretchability.

In an embodiment, the first step in a process to create stretchable andflexible electronics as described herein involves obtaining requiredelectronic devices and components and conductive materials for thefunctional layer. The electronics are then thinned (if necessary) byusing a back grinding process. Many processes are available that canreliably take wafers down to 50 microns. Dicing chips via plasma etchingbefore the grinding process allows further reduction in thickness andcan deliver chips down to 20 microns in thickness. For thinning,typically a specialized tape is placed over the processed part of thechip. The bottom of the chip is then thinned using both mechanicaland/or chemical means. After thinning, the chips may be transferred to areceiving substrate, wherein the receiving substrate may be a flatsurface on which stretchable interconnects can be fabricated. FIG. 3illustrates an example process, which begins by creating a flexiblesubstrate 302S on the carrier 308S coated with a sacrificial layer 304S(FIG. 3A), placing devices 310S on the flexible substrate (FIG. 3B), andperforming a planarization step in order to make the top surface of thereceiving substrate the same height as that of the die surface (FIG.3C). The interconnect fabrication process follows. The devices 310Sdeposited on the receiving substrate are interconnected 312S which joinbond pads from one device to another (FIG. 3D). In embodiments, theseinterconnects 312S may vary from 10 microns to 10 centimeters. Apolymeric encapsulating layer 314S may then be used to coat the entirearray of interconnected electronic devices and components (FIG. 2E). Theinterconnected electronic devices are then released from the substrateby etching away sacrificial materials with a solvent. The devices arethen ready to undergo stretch processing. They are transferred from therigid carrier substrate to an elastomeric substrate such as PDMS. Justbefore the transfer to the new substrate, the arrays are pre-treatedsuch that the device/component islands preferentially adhere to thesurface leaving the encapsulated interconnects free to be displacedperpendicular to the receiving substrate.

In embodiments, the interconnect system is a straight metal lineconnecting two or more bond pads. In this case the electronic array istransferred to a pre-strained elastomeric substrate. Upon relaxation ofthis substrate the interconnects will be displaced perpendicular to thesubstrate, thus producing outward buckling. This buckling enablesstretching of the system.

In another embodiment, the interconnects are a serpentine pattern ofconductive metal. These types of interconnected arrays need not bedeposited on a pre-strained elastomeric substrate. The stretchability ofthe system is enabled by the winding shape of the interconnects.

Stretchable/flexible circuits may be formed on paper, plastic,elastomeric, or other materials with the aid of techniques including butnot limited to conventional photolithographic techniques, sputtering,chemical vapor deposition, ink jet printing, or organic materialdeposition combined with patterning techniques. Semiconductor materialswhich may be used to make circuits may include amorphous silicon,polycrystalline silicon, single-crystal silicon, conductive oxides,carbon nanotubes and organic materials. In embodiments, theinterconnects may be formed of electrically conducting film, stripe,pattern, and the like, such as on an elastomer or plastic material,where the film may be made to buckle, deform, stretch, and the like, asdescribed herein. In embodiments, the interconnect may be made of aplurality of films, such as on or embedded in the flexible and/or astretchable substrate or plastic.

In embodiments, the interconnection of device islands 402S may utilizean extremely stretchable interconnect 404S, such as shown in FIG. 4, andsuch as the various configurations disclosed in the '922 application.The geometry and the dimension of the interconnects 404S is what makesthem extremely compliant. Each interconnect 404S is patterned and etchedso that its structural form has width and thickness dimensions that maybe of comparable size (such as their ratio or inverse ratio notexceeding about a factor of 10); and may be preferably equal in size. Inembodiments, the interconnect may be formed in a boustrophedonic stylesuch that it effectively comprises long bars 408S and short bars 410S.This unique geometry minimizes the stresses that are produced in theinterconnect when subsequently stretched because it has the effectiveform of a wire, and behaves very differently than interconnect formfactors having one dimension greatly exceeding the other two (forexample plates). Plate type structures primarily relieve stress onlyabout a single axis via buckling, and withstand only a slight amount ofshear stress before cracking. This invention may relieve stress aboutall three axes, including shears and any other stress. In addition,because the interconnect may be formed out of rigid materials, afterbeing stretched it may have a restorative force which helps prevent itswire-like form from getting tangled or knotted when re-compressing tothe unstretched state. Another advantage of the boustrophedonic geometryis that it minimizes the initial separation distance between theislands. In embodiments, the interconnects may be formed eithermonolithically (i.e., out of the same semiconductor material as thedevice islands) or may be formed out of another material.

In another embodiment the elastomeric substrate may comprise two layersseparated by a height 512S, such as shown in FIG. 5. The top “contact”layer contacts the device island 502S, where the device islands 502S areinterconnected 504S with one of the interconnection schemes describedherein. In addition, the bottom layer may be a “wavy” layer containingripples 514S or square waves molded into the substrate 508S duringelastomer fabrication. These waves enable additional stretching, whoseextent may depend on the amplitude 510S and wavelength of the wavespattern-molded in the elastomer.

In embodiments, the device island may be any prefabricated integratedcircuit (IC), where the IC may be mounted on, inside, between, and thelike, a flexible and/or stretchable substrate. For example, anadditional elastomeric layer may be added above the structure as shownin FIG. 5, such as to encapsulate the structure for protection,increased strength, increase flexibility, and the like. Electricalcontacts to embedded electrical components may be provided across theembedded layer, through the elastomeric layer(s) from a secondelectrical interconnection layer, and the like. For example, an IC maybe encapsulated in a flexible material where the interconnects are madeaccessible as described in the '849 application. (Se FIG. 1 of the '849application for example). In this example the embedded IC is fabricatedby first placing the IC onto a carrier, such as a rigid carrier, andwhere the IC may be a thinned IC (either thinned before the mounting onthe carrier, or thinned while on the carrier). A second step may involvea coating of the IC with some adhesive, elastomer, or other insulatingmaterial that can be flowed onto the IC. A third step may be to gainaccess to the electrical contacts of the IC, such as by laser drillingor other method known to the art. A fourth step may be to flowelectrical conductor into the openings, thus establishing a electricalaccess to the electrical connections of the IC. Finally, the IC thusencased may be freed from the carrier. Now the structure may be moreeasily embedded into a flexible substrate while maintaining electricalconnectivity. In embodiments, this structure may be a flexiblestructure, due to the thinness of the IC, the elastic character of thesurrounding structure, the elastic configuration of the extendedelectrical contacts, and the like.

It should be noted that many of the stretchable electronics techniquesutilize the process of transfer printing, for example, with a PDMSstamp. In embodiments, the present invention may include a method ofdynamically controlling the surface adhesion of a transfer printingstamp, such as described here, and disclosed in the '904 application.Transfer printing stamps have many uses, one of which is to pick up thinfilms of materials (“targets”) from one surface (“initial surface”) anddeposit them onto another surface (“final surface”). The pickup may beachieved by pressing the transfer printing stamp into contact with thetargets, applying some pressure to create Van der Waals bonds betweenthe stamp and the targets, peeling off the stamp with the targets, andthen placing the stamp with targets into contact with another surface,applying pressure, and peeling off the stamp without the targets so theyremain on the final surface. If the final surface has a higher bondingstrength with the targets than the transfer stamp, they will remain onthe final surface when the transfer stamp is peeled off. Alternately,the rate of peeling the transfer stamp can be adjusted to vary thetarget to stamp and target to final surface bonding force ratio. Thepresent invention describes a novel method of depositing the targets, bychanging the surface adhesion of the transfer stamp after the targetshave been picked up. This may be done while the stamp with targets is incontact with the final surface. In embodiments, the adhesion control canbe done by introducing micro-fluidic channels into the transfer stamp,so that water or other fluid can be pumped to the surface of the stampfrom within it, thereby changing the surface adhesion from sticky tonon-sticky.

In embodiments, the present invention may accomplish transfer printingby using a transfer printing stamp that has been formed withmicro-fluidic channels such that a fluid (liquid or gas) can be pumpedto the surface of the stamp to wet or chemically functionalize thesurface and therefore change the surface adhesion of the stamp surface.The transfer printing stamp may be made out of any material, includingbut not limited to poly-dimethyl-siloxane (PDMS) and derivativesthereof. In one non-limiting embodiment, the stamp is a piece of PDMSformed into a cuboid, which may have dimensions ranging from about 1micrometer to 1 meter. For this example, the cuboid is 1 cm×1 cm×0.5 cm(length, width, thickness). One 1 cm×1 cm surface of the cuboid isdesignated as the stamping face. By using a photolithography mask, or astencil mask, a pattern of vertical holes (channels) is etched from thestamping face through to the opposing face of the stamp. This may bedone with an oxygen reactive ion etch. These holes are the micro-fluidicchannels, and may be about 0.1-10 micrometers in diameter. They may bespaced apart by about 1-50 micrometers. Another piece of PDMS may beformed into a reservoir shape (eg. a 1 cm×1 cm×0.5 cm cuboid with asmaller cuboid (about 0.8 cm×0.8 cm×0.3 cm) cut out from one surface).This shape may be formed by pouring the PDMS into a mold, curing it, andremoving it from the mold. This additional piece of PDMS may then beplaced into contact with the first piece of PDMS and bonded (this may bedone via ultraviolet ozone exposure or oxygen plasma exposure of thePDMS prior to contacting the two pieces) such that the two pieces formthe shape shown in FIG. 6, step A. Then, one or more holes may bepunctured into the top of the reservoir so that a fluidic pipe can befitted for pumping water into the stamp. In another non-limitingembodiment, the stamp is constructed as described above, except that thefirst piece of PDMS is formed to have micro-fluidic channels by means ofmolding. PDMS molding is a well known art. First, a mold is created thatis the inverse of the desired shape. In this case, that is an array ofvertical posts on a base with four walls. This mold is then filled withPDMS by pouring in the PDMS, allowing it to cure (which may be atelevated temperature), and then removing the PDMS. In anothernon-limiting embodiment, the stamping surface is also patterned with anarray of shallow-etched surface channels. In embodiments, these channelsmay be about 100-10000 nm wide, and 100-10000 nm etched-into the PDMS.They may form a linear array or a checkerboard grid. The purpose of thechannels is to help distribute a liquid from the vertical micro-fluidicchannels around the surface of the stamp. In addition, these channelsserve to allow an exit for the air that must be displaced to push theliquid to the surface of the stamp. An example of a liquid that may beused includes, but is not limited to, water (which will wet the surfaceof the stamp and decrease its adhesivity). In the case of a gas fluid,these surface channels may not be necessary. Examples of gasses that canlower the surface adhesion of PDMS are dimethyldichlorosilane (DDMS),perfluorooctyltrichlorosilane (FOTS),perfluorodecyltris(dimethylamino)silane (PF10TAS), and perfluorodecanoicacid (PFDA), and the like.

In embodiments, the stamp may be operated as shown in FIG. 6. First, itis pressed into contact with a substrate that has the target material ordevices to be picked up. (FIG. 6A). The target material is picked up byVan der Waal's forces between itself and the stamp as is well known(FIGS. 6B,C). Target material is placed in contact with the finalsubstrate, and pressed into contact (FIG. 6D). The fluid (for example,water) is pumped to the stamp surface, to reduce adhesion (FIG. 6E). Thestamp may be left in this state (of contact with water) for as long asnecessary for the water to fully wet the stamp surface. Finally, thestamp is removed, leaving the target material behind on the finalsubstrate (FIG. 6F). In FIG. 6A-F, the following labels are made forclarity: fluid inlet 601S; PDMS stamp 602S; fluid distribution reservoir603S; micro-fluidic channels to stamp surface 604S; adhesive stampsurface 605S; devices to be picked up and transfer printed 6; initialsubstrate 607S; final substrate 608S; pump in water 609S so it reachesthe end of the micro-fluidic channels to alter the surface adhesion ofthe transfer stamp and release the devices. Note that any surfacechannels on the stamp surface are not shown in the Figure, and theFigure is not drawn to scale.

Another example of configurations to enable stretchable circuitry are asdescribed in the '125 application in connection with an extendableinterconnect. (See FIG. 3 of the '125 application). The electricalcomponent may be considered as one of a plurality of interconnectednodes, whose interconnections expand/extend as the underlying flexiblesubstrate expands. In embodiments, flexible and stretchable electronicsmay be implemented in a great variety of ways, including configurationsinvolving the substrate, the electrical components, the electricalinterconnects, and the like, and involve electrical, mechanical, andchemical processes in their development and implementation.

As amply discussed herein, CMOS devices offer a variety sophisticatedfunctionality including sensing, imaging, processing, logic, amplifiers,buffers, A/D converters, memory, clock and active matrix switchingtransistors. The electronic devices or the “device islands” of thestretchable/flexible circuitry of the present invention may be devicesand are themselves capable of performing the functionality describedherein, or portions thereof.

In embodiments, devices and device islands, devices are to be understoodas “active” as described above.

In embodiments, the electronic devices are optionally laid out in adevice island arrangement, as described herein. The functionalitydescribed herein with respect to circuitry 1000S and thus electronicdevices may thus be present in an electronic device itself, spreadacross arrays of electronic devices and/or device components, orachieved via electronic communication and cooperation with otherelectronic devices and/or device components each electronic device (orelectronic device and device component combination) having separate oradditive, but complementary functions that will become apparent fromthis disclosure. In embodiments, such electronic communication could bewireless. Therefore, said devices may comprise a transducer,transmitter, or receiver capable of such wireless transmission.

Returning to FIG. 1, this figure schematically depicts the functionalityof the circuitry 1000S (and thus the electronic devices, devicecomponents, or combinations thereof). Elements 1100-1700 and their subelements and components including electronic devices, device components,or combinations thereof may be present in the circuitry 1000Sindividually or in any combination as applicable. Certain combinationswill be discussed below; however, the below discussions merely depictexemplary embodiments of the present invention and thus they aretherefore not to be considered limiting of its scope. It will be readilyappreciated that the elements of circuitry 1000S, as generally describedherein, could be arranged and designed in a wide variety of differentconfigurations. Nonetheless, the invention will be described andexplained with additional specificity and detail.

Circuitry 1000S comprises sensors (alternatively termed “sensordevices”) 1100 to detect various parameters. Thus, to achieve thedetection parameters, sensors may include thermistors, thermocouples,silicon band gap temperature sensors, thin-film resistance temperaturedevices, LED emitters, optical sensors including photodetectors,electrodes, piezoelectric sensors, ultrasonic including ultrasoundemitters and receivers; ion sensitive field effect transistors, andmicroneedles.

The separation distance between sensors (e.g., sensor device islands)can be any that is manufacturable, a useful range may be, but is notlimited to, 10 μm-10000 μm. In embodiments, sensors 1100 can becharacterized as sensor circuits. Individual sensors may be coupled to adifferential amplifier, and/or a buffer and/or an analog to digitalconverter. The resulting sensor circuits may be formed on the same, ordifferent, devices than the sensors themselves. The circuits may be laidout in an active matrix fashion such that the readings from multiplesensors 1100 can be switched into and processed by one or a fewamplifier/logic circuits. Signals from the array of sensors 1100 (or anydevices herein) can be processed using multiplexing techniques,including those described in published international patent applicationWO2009/114689 filed Mar. 12, 2009 the entirety of which is herebyincorporated herein by reference. Multiplexor component circuitry may belocated on or within the circuitry 1000S on the substrate 200, or at alocation that avoids interference with the operation of the device suchas for example at the base of a catheter guide wire although other areasthat avoid interference with operation will be apparent.)

Circuitry 1000S comprises processing facility 1200 (alternativelyreferred to herein as “processor”, “processing”, and the terms mentionedimmediately below) which may include a signal processor, digitalprocessor, embedded processor, microcontroller, microprocessor, ASIC, orthe like that may directly or indirectly facilitate execution of programcode or program instructions stored thereon or accessible thereto. Inaddition, the processing facility 1200 may enable execution of multipleprograms, threads, and codes. The threads may be executed simultaneouslyto enhance the performance of the processing facility 1200 and tofacilitate simultaneous operations of the application. By way ofimplementation, methods, program codes, program instructions and thelike described herein may be implemented in one or more thread. Thethread may spawn other threads that may have assigned prioritiesassociated with them; the processing facility 1200 may execute thesethreads based on priority or any other order based on instructionsprovided in the program code. The processing facility 1200 (and/or thecircuitry 1000S in general) may include or be in electroniccommunication memory that stores methods, codes, instructions andprograms as described herein and elsewhere. The processing facility 1200may access a storage medium through an interface that may store methods,codes, and instructions to perform the methods and functionalitydescribed herein and elsewhere. Processing facility 1200 comprised in oris in electronic communication with the other elements of the circuitry1000S including the electronic devices and/or device components.Off-board processing facility 1200A comprises all the functionalitydescribed above; however, is physically separate from circuitry 1000Syet in electronic communication thereto.

Data collection facility 1300 (and off-board data collection facility1300A) are configured to each independently or both collect and storedata generated by the circuitry 1000S and the elements thereof includingimaging facility 1600 (discussed below), and therapeutic facility 1700.Data transmission facility 1500 includes a means of transmitting (RFand/or wired) the sensor information to processing facility 1200 oroff-board processing facility 1200A. Each of the elements 1100-1700 arealso configured to be in electronic communication with one another andneed not necessarily communicate through the data transmission facility1500. In embodiments, circuitry 1000S and/or data transmission facility1500 is in electronic communication with output facility 300 which, inembodiments, can be in electronic communication with processing facility1200A or a separate processing facility. The various outputs describedherein should be understood to emanate from the output facility 300.

In embodiments, circuitry 1000S may be connected or otherwise inelectronic communication with external/separate devices and systems byphysical connection, including the methods described above and byproviding conductive pads on the circuitry 1000S in an accessiblelocation or location that avoids interference with the operation of thedevice and interfacing anisotropic conductive film (ACF) connectors tothe conductive pads. Also, the circuitry 1000S and/or associated devices10105 may comprise a transducer, transmitter, transceiver, or receivercapable of wireless transmission and thus wireless communication withexternal/separate devices and systems. In addition, circuitry 1000Sislands may be made to perform optical data communication down awaveguide, such as the one described below.

Power source 400 can supply power to circuitry 1000S in any number ofways, including externally optically, with a waveguide and having PVcells made in a stretchable/flexible format in addition to the rest ofthe circuitry. Alternately, thin film batteries may be used to power thecircuitry 10005, which could enable an apparatus to be left in the bodyand communicate with the operator. Alternately, RF communicationcircuits on the apparatus may not only be used to facilitate wirelesslycommunication between devices within the circuitry and/or toexternal/separate systems, but they may also receive RF power to powerthe circuits. Using such approaches, the need for external electricalinterfaces may be eliminated.

Circuitry 1000S includes therapeutic facility 1700 in embodiments of theinvention, include various elements to effect a desired therapy. Inembodiments, circuitry can comprise heat or light activateddrug-delivery polymers that when activated could release chemicalagents, such as anti-inflammatory drugs, to local sites in the body.Therefore, in embodiments, light emitting electronics (such as LED)could be utilized to activate a drug delivery polymer.

In embodiments of the invention, circuitry 1000S comprises imagingcircuitry 1600. Imaging circuitry 1600 in embodiments comprises a packedarray of active pixel sensors. Each pixel in the array may contain aphotodetector, a pn junction blocking diode, an active amplifier, and ananalog to digital converter, formed in a single piece of singlecrystalline silicon (50×50 μm2; 1.2 μm thick). In embodiments, Imagingcircuitry 16000 may be encapsulated with a polymer layer such as PDMS toprevent contact stress induced damage. Imaging circuitry 1600 cancomprise an array of photodetectors on the substrate 200 positioned inclose proximity to the site of interest within the subject's body 2000can provide high spatial resolution imaging without the need for alens-based focusing due to the proximity of the photodetectors to thetissue. Imaging circuitry 1600 comprise a light source comprising orconnected to an optical fiber or an LED to provide illumination to thephotodetectors for imaging the tissue of interest.

Exemplary configurations for the circuitry 1000S including imagingfacility 1600 methods, configurations as well as fabrication techniqueswill be described below. However, it should be understood that anyembodiment of circuitry (and therefore its electronic devices,components, and other functional elements) described herein in shallapply to any of the exemplary embodiments. The exemplary configurationsand techniques are not to be considered limiting of scope. It will bereadily appreciated that the circuitry elements, configurations, andfabrication techniques of the present invention, as generally describedherein, could be utilized, arranged or otherwise implemented in a widevariety of different ways. Also, and by way of clarification, thecircuitry configurations and functional elements as well as thefabrication techniques described for this (and all exemplaryembodiments) described herein shall be considered to apply to each orany of the embodiments disclosed herein and as such should not beconsidered as uniquely and exclusively applying to the particularexemplary embodiments being described.

Embodiments of the imaging facility 1600 may involve a non-planarelectronic imaging array composed of flexible and stretchable electroniccomponents. The flexibility and stretchability of the array enablescurved configurations. These arrays may be integrated into a number ofimaging systems including microscopes, surveillance systems, endoscopes,infra-red imagers, telescopes, sophisticated cameras, scanners, machinevision systems, vehicle navigation systems, computer input devices, autofocus systems, star trackers, motion detection systems, imagestabilization systems and data compression systems for high-definitiontelevision, and the like. The stretchable electronic components areprimarily in the form of active and/or passive pixel arrays which can beincorporated into the imaging systems detailed above. The electroniccomponents may be arranged in islands, which house required circuitryand are interconnected mechanically and electronically viainterconnects. The interconnects, in turn, preferentially absorb strainand thus channel destructive forces away from the device islands. Theyprovide a mechanism by which the integrated circuits can stretch andflex when a force is applied. The present invention primarily referencesthe device islands which consist of one or more pixel units for imagingpurposes. However, stretchable electronic devices and device componentswhich may be incorporated into an “island” are not limited to thisdescription. The device islands and interconnects may be integrated intothe structure of the end product or system level device by transferprinting. This is described further herein. Encapsulation of electronicdevices and system/device interconnect integration may be performed atany of a number of stages in this process.

The circuitry used in the imaging array and accompanying electronicdevices may comprise standard IC sensors, transducers, interconnects andcomputation/logic elements. These devices are typically made on asilicon-on-insulator (SOI) wafer in accordance with a circuit designimplementing the desired functionality. Alternatively, the semiconductordevices may be processed on suitable carrier wafers which provide a toplayer of ultrathin semiconductor supported by an easily removed layer(eg. Polymethyl methacrylate, PMMA). These wafers are used to fabricateflex/stretch ICs by standard processes, with island and interconnectplacement being tailored to the requirements of a particularapplication.

A representative, non-limiting example of fabrication steps utilized increating an electronic device in accordance with the present inventionis as follows. It will be appreciated by one skilled in the art thatother stretchable electronics methods as described herein may bealternately applied in the creating a non-planar imaging device inaccordance with the present invention.

In embodiments, electrical devices may be laid out in a device “island”arrangement. In, one embodiment of the invention, the device islands maytypically be 1 μm×1 μm-1000 μm×1000 μm in area. However, other featuresizes may be utilized as required. These islands can accommodate atleast one pixel which may include a photo sensing material andassociated circuitry (e.g. transistors, in the case of active pixelarrays). Larger islands may have the capacity to hold more than onecomponent or pixel. The islands may be connected to a buffer and/or anamplifier. Islands may accommodate active matrix switches, A/Dconverters, logic circuitry capable of reading in digital signals andprocessing them, and are capable of outputting data or storing data inmemory cells. Additionally, some islands are simply designed and used asmetal contact pads. At least one electrical and/or mechanicalinterconnection is found between each island.

As shown in FIG. 7A, the image sensors may be fabricated on a planar SOIwafer (e.g. thickness from 100 nm to 100 μm thick; this example is a 1.2μm thick top Si, 1 μm thick buried oxide) using standard CMOSfabrication technology. The image sensors may also be fabricated usingnon-silicon material such as germanium, gallium arsenide, indiumphosphide, lead sulphide, and the like.

As shown in FIG. 8, each pixel 800NP may be laid out in an array 802NP.As shown, the pixel may have control and power contacts, such as for bit804NP and word 808NP selection, and power (Vcc) 810NP and reset 812NP.The array may be laid out such as in a 1 μm×1 μm island array, such asspaced apart by 1-100 μm from any adjacent island, and the like. Afterstretch processing, this inter island gap may be shrunk due tocontraction of the entire array. Pixel dimensions may vary within thelimits of island size (e.g. 1 μm×1 μm-1000 μm×1000 μm in area with anexemplary pixel pitch around 2 μm and thus an island of 100 μm2 willcontain about 25 pixels). FIG. 9 shows an additional active pixel designthat may be used, including a micro-lens 902NP, amplifier transistor904NP, bus transistor 908NP, silicon substrate 910NP, reset transistor912NP, and the like.

One embodiment of the imaging array is a CMOS active pixel array madeusing a 2 metal layer process. The array is designed using rulesspecified for the integration of mechanical bridges and electricalinterconnects into the system. Image sensor grids are fabricated on anSOI wafer separated by gaps (FIG. 7B). These gaps facilitate theformation of stretchable interconnects at a later stage. The siliconunder each gap is then etched away to isolate image sensor islands (FIG.7C). This space may be important when considering the final non-planarshape of the imaging array. In order for the pixels to be evenly spacedin the final non-planar shape, the pixels/island separation may need tobe unequal in the planar layout. Hence, the interconnect between islandsmay be of different lengths. Calculations are done on a case by casebasis to determine the optimal layout of islands in the planar design inorder to achieve uniform density of pixels in the non-planar imagingarray. For instance, the spaces between image sensors may range from 100nm to 100 μm.

In an example, the image sensor islands are protected by a firstpolyimide (PI) passivation layer, then a short HF etch step is appliedto partially undercut the islands (FIG. 7D). The first passivation layeris removed, and then a thin film of SiO2 (100 nm thick) may be depositedand patterned by PECVD or other deposition technique combined with alift-off procedure, such that the oxide layer covers most of the spacebetween device islands except for a region that is about 5 μm wide (FIG.7E). The purpose of this oxide layer is to act as a sacrificial layerduring the final etch step so that the PI that is deposited in the nextstep only adheres to the underlying silicon in a small ˜5 m wide regionthat has sufficient adhesive force to prevent the devices from floatingaway in the HF etch but not too much adhesive force to prevent highyield transfer printing.

A second polyimide layer is spun on and patterned to form the shape ofthe interconnect wires/bridges between the islands (FIG. 7F). Typicallyone bridge may extend from the center of one island edge to the centerof another island edge. This design was used in a passive matrix imagingarray. Alternately, two bridges may extend from each corner of thedevice island to two different device island corners. Other bridgeconfigurations may also be utilized especially for designs which aim toreduce the overall mechanical strain in the final stretchable system(determined by mechanical modeling). One exemplary interconnect designhas a tightly packed serpentine layout and connects from one corner ofan island to the corner of an adjacent island. In embodiments,interconnect bridges may be about 100 nm to 500 μm wide and mayaccommodate multiple electrical lines.

The second polyimide layer partially fills where the device island isundercut; this serves to stabilize the island later in the releaseprocess and to prevent its migration. Vias are etched into the second PIlayer to make metal interconnects. Next, a third metal layer ispatterned to contact the circuits and connect word, bit, reset and vcclines from one island to another (FIG. 7G). In one embodiment of theinvention, the islands are made up of one pixel each. In this examplethe third metal layer contacts points 1-8 through vias as show in theFIG. 10. Vias are made down to the first and/or second metal layers asrequired, facilitating electrical contact between the sensor's word,bit, reset and Vcc lines and the third metal layer. In anotherembodiment of the invention, the islands are comprised of multiplepixels. FIGS. 11-13 illustrate a number of designs which may be usefulfor interconnecting islands with multiple pixels.

In one embodiment of the image sensor, a color filter array (e.g. BayerColor filter array) is then deposited onto each pixel (FIG. 7H). This isaccomplished by using a pigment infused photoresist (eg.diazonaphthoquinone DNQ-Novolac) as done in conventional color filterdeposition. For applications that do not require color images, this stepmay be omitted.

A third PI layer is spun on (covering the wires and everything else)(FIG. 7 i). In one embodiment of the invention, the third PI layer maythen be processed using laser ablation and thermal reflow to create anarray of micro-lenses as shown in (FIG. 7J).

The second and third PI layers are then isolated by etching with adeposited SiO2 hard mask, in O2 RIE. PI located outside device islandsand bridges is etched, as well as PI covering areas that are meant to beexternally electrically interfaced, and small areas leading to theunderlying oxide.

Etch holes may be formed if necessary and then transferred through thesilicon or metal layers by wet and or dry etching. The underlying buriedoxide is etched away using HF etchant to free the devices, which remainattached to the handle substrate due to the second polyimide passivationlayer which contacts the handle wafer near the border around the deviceislands (FIG. 7K).

If the HF etch is not controllable enough and seeps under the PIisolation layer and thereby attacks the CMOS devices, then prior to thesecond PI passivation a brief Argon sputtering can be done to remove anynative oxide followed by amorphous silicon sputtering followed by the PIpassivation and rest of the processing. After rinsing, the devices areleft to air dry. The end result is a network of islands connected bymetal and polymer interconnect system. These islands contain one or morepixels.

It is understood that stretchable circuits may be realized usingtechniques other than those described above, combinations of thetechniques listed above, and minor deviations from the techniquesdescribed above. For example, stretchable circuits may be formed onplastic, elastomeric, or other stretchable materials by sputtering,chemical vapor deposition, ink jet printing, or organic materialdeposition combined with patterning techniques. Semiconductor materialswhich may be used to make circuits may include amorphous silicon,polycrystalline silicon, single-crystal silicon, conductive oxides,carbon nanotubes and organic materials. All of the methods describedabove for enabling stretchable circuits will henceforth be referred toas “stretchable processing”.

Under-etched, ultrathin partially or fully processed circuits fabricatedby one of the methods described above may be transferred from theirsilicon mother wafers to a desired surface via transfer printing, asdescribed herein.

One embodiment of the non-planar imaging array comprises a CMOS imagingsystem. This imaging system may be either active or passive. Thecomponents of the CMOS imaging system follows conventional CMOS imagingtechnology, as known to the art, where the CMOS sensor device convertsan image into a digital image. The sensor usually includes a pixel arraywith transistors and several sensing elements, such as photodiodes. TheCMOS image sensor is composed of a photo-sensing means for sensing lightand a CMOS logic circuit for processing sensed light into electricalsignals to make them as data, where a readout circuit is connected toeach pixel cell. One method in which to create an active matrix imagingarray is done by joining islands with pixel units similar to those shownin FIGS. 8 and 9. FIG. 10 illustrates how one CMOS active pixel may beconnected to a series of neighboring pixels to form an array joined byinterconnects which will ultimately enable stretchability and theability of the array to conform to non-planar configurations. FIGS.11A-C illustrates the example where there are multiple pixel units on anisland connected via metal lines sandwiched between a polymer supportsuch as polyimide. In color camera applications, color filters arerequired since sensors only measure light intensity. Micro-lenses arealso used to increase the amount of light focused onto each pixel. Theselayers can be easily incorporated into the non planar pixel array bywell known techniques. Ultimately the CMOS imaging array is incorporatedinto a larger system such as a camera module and would requiresupporting hardware to create useful information; such as illustrated inFIG. 14, including, image pixels 1002NP, timing 1004NP, bias circuitry1008NP, A/D converter 1010NP, amplifier 1012NP, column multiplexer1018NP, row access 1014NP, and the like.

Another embodiment of the CMOS array is the backside illuminationconfiguration. This configuration incorporates aspects of the originaldesign but instead of having light from the image come through the metallayers, the array is flipped and light is channeled onto each pixel frombehind (closer to the sensing element). This design significantlyincreases the amount of light that reaches a photodiode because lesslight is blocked by metal interconnects and dielectric layers (pixelvignetting) as occurs in conventional front side illuminated imagers asshown in FIG. 15A. This back side illuminated configuration stack designcan be seen in FIG. 15B. Similar to the conventional top illuminatedimage sensor, the backside illuminated pixel requires a color filter inorder to produce color images and benefits from having a microlens arrayon top of the stack to guide more light into the photosensitive parts ofthe imager.

The idea of backside illuminated photodetectors is not a new one.However, manufacturing these inverted detectors uncovers significantchallenges with photodiode/lens/color filter alignment, pad contactforming and wafer thinning which are all required processes. Thestretchable processing technique described in this invention provides amethod by which some of these challenges may be overcome. It isparticularly effective as an alternative to conventional wafer thinningprocesses which suffer from a significant reduction in sensor yield withreducing thickness. The current invention describes a method whichemploys undercut etching and polymer encapsulation to create thindevices and avoid the need for backside grinding of devices.

In order to create a backside illuminated imaging array, the sameprocess may be followed for the front side illuminated array(conventional) up to the point of deposition of the inter-pixel metalinterconnects as illustrated in FIG. 7G. After the deposition of thefinal metal layer, vias are drilled to the oxide layer and the imagesensor islands are undercut. This undercut releases the islands from themother wafer but they are supported by the PI posts that lie beneaththem. The stretch processed image sensor is then flipped over using ageometric transfer stamp as shown in FIGS. 17A-B. The color filter arrayand a microlens array can be fabricated via conventional techniqueswhile stacked on top of a sacrificial layer as illustrated in FIGS.18A-F. The color filter and microlens array are aligned with the sensorarray and the both are bonded together to complete the deviceconstruction as illustrated in FIG. 19. The next step involvesrelaxation of the geometric stamp to form the required curved shape. Thecurved sensor is then packaged as illustrated in FIGS. 20A-C. Otherpotential process flows for creating a backside illuminated imager areillustrated in FIGS. 21-23.

In embodiments, the present invention may provide for a method forfabricating a planar back-side illuminated imager. As shown in FIGS.24A-F, the process for creating a backside illuminated imager beginswith creating photodiodes on top of a sacrificial layer, supported by arigid carrier substrate. In this example, silicon photodiodes arefabricated on an SOI wafer. Dielectric and metal lines are thenfabricated on top of the photodiodes to complete fabrication of theimage sensor. Conventional image sensor designs may be exploited for theprevious mentioned steps. A polymeric material is then used to passivatethe surface of the image sensor. This polymeric material offersmechanical support. An etch step follows, creating small holes to accessthe sacrificial layer (eg. SOI oxide layer). The sacrificial layer isthen removed by chemical action. The image sensor array is now ready tobe flipped, preferably using an elastomeric stamp. The stamp picks upthe image sensor form its carrier substrate and transfers it to anotherstamp which completes the flip. It is subsequently deposited onto aclean second carrier substrate for further processing. At this stage,color filters and micro-lenses may be fabricated using techniques knownto those familiar in the art.

The methods described herein to attain non-planar imaging arrays may beapplied to numerous other imaging array/pixel designs. Commerciallyavailable CMOS imaging array designs may be modified using ourstretchable processing method to give non-planar imaging array formats,such as megapixel imagers, full frame imagers, line imagers, CMOSimagers, CCD imagers, and the like. The modification involves connectionof islands, each containing at least one imaging pixel, with a series ofmetal and polymer interconnects as described above. Connections may bemade through vias which provide a means of accessing buried metal layersand joining them to an inter-pixel interconnect network which allowsdeformation of system.

In accordance with embodiments of the present invention, the non-planarimaging systems may be incorporated into a number ofproducts/applications such as microscopes, semiconductor waferinspection cameras, inspection imaging systems, metrology imagingsystems, surveillance cameras, camera modules for compact cameras (cellphones, web cams, discrete security cameras), medical imagers,endoscopes, blood-flow imagers, nuclear medicine imagers, infra-redcameras and other imagers, ground based telescopes, space-based imagers,digital still cameras, video cameras, scanners, machine vision systems,vehicle navigation systems, video telephones, computer input devices,auto focus systems, star trackers, motion detection systems, imagestabilization systems, pattern recognition systems, web cameras, highdefinition TV imagers and imaging systems for unmanned aerial vehicles(UAVs), active pixel arrays for high definition imaging, automotivecameras, night vision imagers, x-ray imagers, gamma ray imagers,radiation detectors, ultrasound imaging, thermal imaging, and the like.The embodiment of the image sensor in each application may be either inthe form of a packaged image sensor, a camera module (optics componentand imager) or a more complete camera (self sufficient imaging devicewith all software and hardware required for application specificperformance).

The image sensor may be incorporated by two methods. One method involvesdirect incorporation of the imaging array into the camera of the desiredsystem, thereby replacing the planar imaging array with a non-planarimaging array as described in above embodiments. This is done bydepositing metal lines to connect the image sensor's bond pads to theouter rim of its supporting substrate, then bonding an anisotropicconductive film (ACF) connector from these metal lines to the receivingsystems' computing modules. There may be at least one ACF connectorleaving the imaging array that may be connected to a circuit for imageprocessing. Conductive pads in the imaging array's layout areconveniently placed in easily accessible regions close to the perimeterof the array. If the pads are covered by an encapsulation layer such asPDMS they may be accessed via wet or dry chemical etching, mechanicalremoval of material, including but not limited to drilling, or bylaser/heat ablation.

The second method for incorporating the curved sensor array into aproduct is to package the image sensor in a more conventional chip scalepackage such as ball grid array (BGA) as shown in FIGS. 16A-F and 20A-C.In accordance with the above embodiment, metal lines are created tocontact the image sensor's bond pads to the outer rim of its supportingsubstrate. Subsequently, ACF connectors are fused to these metal linesand connected to a 32 pin contact that is linked to the BGA laminate forcommunication with external components. The BGA substrate typicallyconsists of two or more insulated metal layers (copper coveredbismaleimide triazine (BT) laminate). The laminate is bonded to a seriesof copper balls on its underside. Vias are drilled into the substratethrough to the copper balls to facilitate a direct path the 32 pincontact pad and conductive balls. In order to stabilize and secure theunderside of the curved image array and its ACF interconnects, aprotective epoxy may be applied. The BGA form of the curved imager willbe more readily acceptable into a multitude of products and may open thepossibility of addressing systems not designed specifically for theuniquely shaped imagers. Other types of BGAs may be used, such as wellunderstood by one skilled in the art.

In accordance with the embodiment of the invention referring to anon-planar image sensor incorporated into a camera module as shown inFIGS. 25A-B. The packaged image sensor (e.g. BGA) is directly integratedinto a circuit board which houses components including an imageprocessing device, random access memory and interfacing logic hardware.This is done by aligning the ball contacts at the bottom of the BGA withthe contacts of the circuit board then applying heat for the balls tomelt and make permanent bonds.

Finally, a lens barrel containing at least one lens, is aligned with theimage sensor. The lens barrel contains adjustable mounts which canchange the distance between the lens(es) and the imaging array to changefocus. The three components may be produced separately then assembled.The lens barrel has at least one lens on a moveable mount. This lens maybe either glass or plastic. The lens is designed to be easily snappedinto the moveable mount during assembly. In one embodiment the lens andits plastic holder may be extruded together.

One embodiment of the camera module has at least one injection moldedplastic optic/lens which can be readily made to various curvatures andsizes before insertion into the lens barrel. A metal mold is fabricatedwith a hollow lens-shaped cavity that is filled by injecting polymer ina semi-liquid form. The polymer is allowed to set or cure before openingthe mold and removing the part. This process is done under high pressureand the polymer lens requires little finishing work before it is setinto place on the moveable mount of the lens barrel. Yet anotherembodiment of the camera module has a lens that can change itscurvature. This is achieved by using an encapsulated liquid or gel basedlens which can be put under different radial tensions, thereby changingthe curvature of the lens. Changing the curvature of the lens in thismanner gives a greater focusing capability to the camera module. Theradial tension may be administered via the moveable mounts upon whichthe lens is supported.

Another embodiment of the invention relates to a non-planar imagingarray that can be bent dynamically while attached to the rest of thecamera module. This is achieved by encapsulating the image sensor with athick (˜1 mm) and flexible PDMS substrate. The PDMS layer enablesdeflections of the imager with little or no effect on the imagerperformance. The main purpose of such an imager is to morph fordifferent optics heads just as a lens system is adjusted to tune thefocus and magnification of an image. The varying of curvature may beperformed by an actuator similar to that of the moveable mount inmodulating lens curvature in the embodiment discussed above. Theapplication of tension in the imager changes its shape and thus changesthe focus of the camera module. Application of equal radial tension maybe achieved using a mechanical jig which clamps onto the outer rim ofthe imaging array and can be expanded or contracted equally in alldirections to change the curvature of the array without losing symmetry.The substrate which supports the imaging array will also have to bestretchable in this case.

One embodiment of the invention pertains specifically to ultra compactcamera modules for use in cell phones, web cams and discretesecurity/surveillance cameras. The BGA package is commonly used forhousing image sensors that are incorporated into such ultracompactsystems thus making integration a very simple procedure.

There is a need to optimize the curvature of the imaging array to meetapplication specific requirements (e.g. different degrees of imagercurvature). Standard configurations for the shape of these non-planararrays include hemispherical, ellipsoid and paraboloids of revolution.However, the arrays may be fabricated into wider variety of symmetricaland non-symmetrical shapes as long as the system strain does not exceedits maximum capacity which was demonstrated to exceed 150%. There mayalso be a need to optimize the shape and number of lenses in eachsystem. Finally, minor spatial redesign may be required when changingnumber or lenses and shape of imager. This modification can beconsidered minor and most likely would not require a significant amountof innovation.

In embodiments, the present invention may provide for improved methodsfor fabricating a non-planar imaging array. The advantages of anon-planar, or curved imaging arrays is well understood in the art,including a lower number of optical elements (and thus a reduction inweight, size, cost, complexity), reduced aberrations includingastigmatism and coma, an increase in off-axis brightness and sharpness,an increased field of view, and the like. The present invention providesa method by which a non-planar imaging array may be fabricated utilizingimage sensors made with standard semiconductor processes as describedherein, such as for example, CMOS imaging elements or CCD imagingelements made from single-crystalline semiconductor. The presentinvention then fabricates and integrates the image sensors into anon-planar image array from stretchable electronics technologies, asdescribed herein, allowing for the creation of an optical system thatbenefits from both standard high quality semiconductor processing of theimage sensor, and from the advantages of non-planar imaging arrays asrealized through utilization of stretchable electronics technologies.These benefits may be realized in a plurality of optical systems, suchas listed herein, especially where reduced weight and size, andincreased field-of-view are important, such as for example, opticalsystems in security systems, inspection and metrology systems, spaceapplications, manned and unmanned vehicles, medical vision systems suchas endoscopy, and the like. In addition, many other imaging applicationsmay benefit from the lower cost/size/weight of a system fabricated bythe present invention, such as for mobile devices including cell phones.The present invention may also provide benefits to more sophisticatedsystems, such as in telescopes, where the benefits as previouslymentioned may be realized along with the ability to actuate the imagesurface, as in for instance, adaptive optics. One skilled in the artwill appreciate that combinations of the benefits offered by the presentinvention can be applied across the spectrum of optical systems, andthat these examples are meant to be illustrative, and not limiting inany way.

In embodiments, a medical vision system may be implemented and gainbenefit from the present invention, such as for example, in endoscopy.Referring to an endoscopic imager as described herein, it can be seenthat a non-planar imager mounted on an endoscope or imaging endoscopiccapsule, can be implemented with the present invention. Here, thenon-planar imager may be presented on the surface of the endoscope orendoscopic capsule, such as in a concave or convex configuration. Atechnician reading the images sent back from a procedure utilizing oneof these devices may now have all the benefits provided by the presentinvention, including increased field of view (due in part to the curvedimage surface), increased image quality (due in part to the benefits ofnon-planar imaging and from high quality image sensors), increasedperformance in dim light conditions (due in part to the high qualityimage sensors), and the like. The non-planar imager of the presentinvention may enable the image array to be formed on a plurality ofmedical device surfaces, and still maintain a high quality imageproduct, such as being mounted on different probes, catheters, implants,and the like. In embodiments, the present invention may provide animprovement to both the image quality and field-of-view in medicalimaging devices.

In embodiments, security imaging devices may benefit from the presentinvention. For example, a security imaging device may have therequirements for high resolution, large field-of-view, and small size.Such a set of requirements may be better met with the present invention,such as providing high resolution through standard high quality imagesensor elements, large field-of-view through a non-planar focal plane,small size through the minimizing of optics, and the like. The securitycamera may also benefit from the low light capabilities of standardimage elements as integrated into the imaging array

In embodiments, the present invention may be applied to inspection andmetrology systems, where a larger field-of-view may be required whilemaintaining high quality and high-resolution imaging. These requirementsmay typically dictate that a planar imager be placed a significantdistance from the objects being imaged in order to maintainfield-of-view requirements, and so take up room in a facility that couldotherwise be used for other functions, or without which the inspectionand/or metrology system might be made smaller. However, a non-planarimager of the present invention may provide for a significantly greaterfield-of-view, and so the non-planar imager may allow for a shorterobject distance for the same field frame. At the same time, thenon-planar imager of the present invention may allow for high qualityimages due to the use of standard image sensor fabrication techniques.In this way, the present invention may provide for high quality imagesin a smaller space with shorter object distance. In an example, thepresent invention may provide for metrology imaging in the process ofsemiconductor chip manufacture. Here, the non-planar imager of thepresent invention may be mounted closer to the wafer and so demand lessvolume in which to implement the required imaging system. In addition,the non-planar imager of the present invention may be lighter due to aminimization of lenses required by the system, and so if the imagerneeds to be placed into motion as part of its function, it will have alower inertia, and so the drive system requirements may be reduced. Inembodiments, the present invention may provide reduced weight andincreased field-of-view while maintaining high quality images toinspection and metrology applications. In addition, the reduction inlenses required of the non-planar imager may provide a system that isless costly and more reliable.

In embodiments, the present invention may provide for imaging systemsfor space-based imaging applications, such as for telescopes in sciencemissions, surveillance imaging for the military, star trackers forspace-based navigation, on-board telemetry imaging for spacecraft andpayload state of health and operation, and the like. Spacecraft aredesigned with critical attention given to weight and volume of allcomponents, and use of a non-planar imager of the present invention mayprovide significant advantages with respect to both of theserequirements, where weight and volume are both potentially reduced withthe minimization of lenses as a result of the non-planar array. At thesame time, image quality need not be compromised as the presentinvention may allow for the use of high quality semiconductor imagingelements from standard fabrication processes. In an example, astar-tracker is typically required as a part of the spacecraft guidanceand navigation system, and uses essentially a telescope to image thestar field for celestial navigation. The imaging requirements for a startracker are therefore quite high, and so the system typically requires alens system which consumes a significant mass and volume. However, anon-planar imager of the present invention may be able to reduce themass and volume associated with the optical system, and provide a massand volume savings to spacecraft design resources. In embodiments, dueto the potential for reducing mass and volume due to a minimized needfor a lens system, the present invention may provide improvedspace-based imagers for spacecraft applications.

In embodiments, the present invention may provide benefits to imagersassociated with manned and unmanned vehicles, such as for imagers thatprovide different views from the vehicle. In manned vehicles, such ascars, trucks, trains, subways, busses, boats, and the like, camerasequipped with imagers of the present invention, being potentiallysmaller and lighter, may be able to more easily be integrated into thevehicle to provide views from which the driver has limited or novisibility, and for unmanned vehicles may provide all or any views fromthe vehicle. In an example, an automotive designer may provide anon-planar imager on a back of a car, such as on the bumper, on thetruck, integrated with a back light, so that the driver can have a viewof what is directly behind them, such as for backing up, parking, andthe like. The non-planner imager may also provide a wider field of viewfor the driver than would be provided by a traditional planar imagingsystem. In embodiments, the present invention may provide for advantagesover traditional planar imagers such that cameras are easier and moreconvenient to install, less expensive, provide for a greater field ofview, and the like.

In embodiments, the present invention may be applied to products andcomponents that are constrained in allowable volume or which wouldbenefit from a reduction in size. In an example, cell phone cameras arevery constrained with regard to volume, as they need to produce as higha quality of image as possible in a very small volume. The lens of sucha camera typically takes up a portion of that volume. However, by usinga non-planar imager of the present invention, the lens system may besignificantly minimized. This would not only free up the volumepreviously allocated to the optics system, but also reduce the cost ofthe phone. In another example, an image device such as a night visionscope is typically constrained to how small it can be made by the opticssystem. In this case, the present invention may be able to provide animager that does not require a large optics system, and thus potentiallyreducing the size, weight, and cost of the device. In embodiments, thepresent invention may provide a way to reduce the size, weight, and costof any imaging system that currently utilizes a planar imager andassociated optics. As such, the present invention may provide generalbenefits to any optics system.

The application examples provided herein are meant to be illustrative ofthe plurality of benefits that may be enabled through the use ofnon-planar imagers of the present invention. As such they are not meantto be limiting in any way. Given these few examples, one skilled in theart will appreciate that the present invention may be applied to thegreat scope of today's optical systems, which may each benefit from allor a subset of the benefits provided from use of non-planar image arraysas described herein.

Referring now to a more detailed embodiment for endoscopic imagingapplications, the imaging facility 1600 may involve endoscopic imagingdevices having improved design efficiencies in terms of power andvolume. As such all imaging-related embodiments described above areintended to be used with (be it additionally or alternatively) with theendoscopic imaging device, systems, and methods described below.Therefore, the specific descriptions below are meant to comprise oneexample of an endoscopic imaging device and shall not limit theendoscopic imaging device to those particular embodiments describedbelow.

Embodiments of the present invention incorporate conformal, curvilinearelectronic components for the purpose of volume reduction, imagingenhancement, and increased functionality.

It will be appreciated that the approach of the embodiment describedbelow may be applied to conventional tubular endoscopy devices andcapsule endoscopy devices, as well as any device utilizing the hereindescribed curved focal plane arrays of photodetectors that are comprisedin an imager, such as a CMOS, CCD, and the like imager as describedherein. Note that the terms ‘curved focal plane array’ and ‘curvedoptical sensor array’ are used interchangeably with ‘non-planar imager’as described herein. It should be noted that such curved focal planearrays can be utilized in conjunction with any embodiment describedherein and that all other embodiments described herein including thoserelated to the circuitry including and the elements thereof are intendedto be utilized as applicable in the endoscopy embodiment describedbelow. As described herein, curved silicon optical sensor arrays havesignificant advantages over conventional planar arrays. These advantagesinclude a reduced number of optical elements, reduced aberrationsincluding astigmatism and coma, and increased off-axis brightness andsharpness.

In embodiments of the invention, an endoscopy device is fitted with acurvilinear array of sensors and/or transducers, e.g., on the exteriorsurface thereof, thereby reducing the required volume of the device.This approach is particularly advantageous in reducing the overall sizeof an endoscopy device, allowing integration of additional diagnosticand therapeutic and/or sensing functionality including any describedherein an the following examples, ultrasound, pressure sensing,temperature sensing, pH, chemical sensing, targeted drug delivery,electrocautery, biopsy, laser, and heating), and increasing theallowable battery size. Increasing the power storage of a capsuleendoscopy device can lead to improvements in image quality, imagecompression, transmission rate, number of images captured, and theintensity of illumination produced by the LEDs.

In embodiments of the invention, a capsule endoscopy device and itsinternal circuitry are both made flexible and/or stretchable from any ofthe materials described for substrates including other biocompatiblematerials apparent to those skilled in the art. Such aflexible/stretchable endoscopy device may have increased ease of motionalong the GI tract and also increased viable volume. In otherembodiments, the device may have a rigid capsule-like structure withelectronics conformally fitted in the inner and/or outer shell of thecapsule. The exposed surface—either a rigid ellipsoid shell or aflexible or stretchable layer—is fabricated from a material resistant tothe harsh digestive environment that the endoscopy device willencounter, but which is also is biocompatible and harmless to thepatient's internal anatomy. Other properties of biocompatibility of theouter surface are described herein.

The stretchable electronic components of the endoscopy device have beendescribed herein in connection with the discussion of circuitry in allembodiments. In embodiments, circuitry comprises sensing and imagingarrays for monitoring features that are inside of bodily cavities andlumen such as the GI tract. As described above, the functionality mayreside in circuitry comprising devices which may comprise device islandsor vice verse. The islands house required circuitry and areinterconnected mechanically and electronically via interconnects such asthose described herein. The interconnects, in turn, preferentiallyabsorb strain and thus channel destructive forces away from the deviceislands. They provide a mechanism by which the integrated circuits canstretch and flex when a force is applied. The device islands andinterconnects may be integrated into the casing or encapsulating shellof the endoscopy device by transfer printing, as described below.Encapsulation of electronic devices and system/device interconnectintegration can be performed at any of a number of stages in thisprocess.

As with other embodiments described herein, the circuitry used in theelectronic devices may comprise standard IC sensors, transducers,interconnects and computation/logic elements. In embodiments, electronicdevices are typically made on a silicon-on-insulator (SOI) wafer inaccordance with a circuit design implementing the desired functionality.Semiconductor devices may be processed on suitable carrier wafers whichprovide a top layer of ultrathin semiconductor supported by an easilyremoved layer (eg. PMMA). These wafers are used to fabricateflex/stretch ICs by standard processes, with particular island andinterconnect placement being tailored to the requirements of aparticular application. “Ultrathin” refers to devices of thin geometriesthat exhibit extreme levels of bendability. They are typically less than10 μm in thickness.

The above discussions of fabrication of circuitry applies to endoscopyembodiments. However, the following discussion will describe a transferstep for embodiments related to endoscopy (but not necessarily limitedthereto). In such embodiments, the circuitry is primarily used toenhance the imaging system of the device.

Imaging with a curved optical sensor array (instead of a planar array)may be used in conjunction with a lens, illuminating LEDs, battery,computing unit, antenna and a radio transmitter. Wired telemetry is usedfor conventional tube endoscopy. A passive or active matrix focal planearray is fabricated using one of the stretchable processing techniquesdescribed above. The array includes single-crystal siliconphoto-detectors and current-blocking p-n junction diodes. Imagescaptured using the array are minimally processed by onboard computingand transmitted (wired or wireless) to an external receiver for furtherprocessing.

The focal plane array described below could be considered part of anyimaging facility described above. The individual photo detectors orelements may be networked via interconnect systems in accordance withthe present invention. These devices are found on islands and areconnected by interconnects such as those interconnects described herein.In embodiment, films of polyimide support certain regions andencapsulate the entire system. Such a focal plane array can thus beincorporated into the endoscopy device.

FIG. 34 illustrates a process of making such focal plane array. Thefirst step is fabricating the necessary circuitry 1000E, which in thisembodiment is a focal plane array, is the creation of a suitablegeometric transfer stamp to facilitate this process. In this embodiment,the circuitry is represented herein as 1000E (although it should beunderstood that is contemplated that this circuitry 1000E relates to andmay be used with other circuitry embodiments described herein).

At Step 1600A, an appropriate stamp (also referred to as transferelement) 240E is created by casting and curing poly(dimethylsiloxane)(PDMS) in the gap between opposing convex and concave lenses withmatching radii of curvature (1621E and 1622E respectively). The radiusof curvature should reflect the optimal parabolic curvature useful for anon-coplanar imager. At step 1600B, the cured curved transfer element240E (the removal of which from lenses stamping mechanism not shown) canbe stretched using a specially designed mechanism which provides outwardradial forces (in embodiments equal outward forces) along the rim of thestamp to create the planar pre-strained geometric transfer element. Thetransfer element should return to its initial size when relaxed.Transfer element 240E should also be large enough in its planarconfiguration to contact the entire area of electronic device islands onthe donor substrate.

A component of the circuitry 1000E in this embodiment is the processedelectronic devices joined by interconnects 1020E. At step 1600C, thecircuitry 1000E is brought into contact with the planar transfer element240E, which adheres to the former via sufficiently strong van der Waalsinteractions. The transfer element 240E is peeled back, thereby removingthe focal plane array, i.e., circuitry 1000E, from its handle wafer1626, shown at 1600D. After the focal plane array 1000E is removed fromthe handle wafer, the tension in the stamp is released and thecontacting layers, i.e., the focal plane array and the stamp, both takeinitial geometric form of the stamp (shown at 1600E). The focal planearray 1000E compresses and the networked interconnects 1020E of thearray buckle to accommodate the strain. The buckled focal plane array1000E is then transferred to its final substrate (shown in steps1600F-H) which has a matching radius of curvature and is also incommunication with the battery, antenna and a radio transmitter viaelectrical contacts. This transfer occurs by contacting both surfacesand is aided by the use of a photocurable adhesive. The adhesiveprovides sufficient attraction such that when the PDMS stamp is removed,it releases the curvilinear array of photodetectors onto the imagingsystem port. The curved focal plane array is then connected to the restof the imaging electronic components via electrode contact pads on theouter perimeter of the array.

In another embodiment shown in FIG. 34A, and endoscopy device 1680Ecomprising power 300E in the form of a battery, processing facility1200E, and data transmission facility 1500E is shown. Step 1601A showsconvex focal plane array 1000E that is adhered to the outer shell of theendoscopy device 1680E by, for example, a geometric transfer stamp 245E.After lifting the focal plane array off the handle wafer with the planarpre-strained PDMS (as described in connection with previous FIG. 34), itcan be relaxed and directly deposited onto the distal end of theendoscopy device 1680E, which is provided with a receiving substrate246E having, for example, a photocurable adhesive. After deposition ontothe endoscopy device 1680E (status shown as 1601B), electrical contactsare made from the array 1000E to the internal circuitry of the endoscopydevice 1680E. At 1601C, all of the exposed circuitry can be sealed witha suitable polymer and/or metal layer (eg. parylene, polyurethane,platinum, gold) 247E.

Micro-lens arrays may be required for such optical array systems.However, with proper illumination and negligible distance between theoptical array and the surface being imaged (e.g. near field imaging),this requirement may be nullified.

In yet another embodiment, a focal plane array, also referred to ascircuitry 1000E (as described above) is conformally wrapped around anendoscopy device such that it points in an outward radial direction fromthe long axis of the device. This is achieved by completing the sameplanar stretchable processing steps mentioned above and transferring thecircuit with a different specialized polymeric stamp. The transfer stampmay take the form of a planar rectangular strip. Each polymeric strip ispre-strained by thermal expansion (heat to around 160° C.) or byapplying uniform radial strain. This pre-strained polymer is thenpositioned in direct contact with the processed focal array. Theelastomer is subsequently peeled back to release the array from itshandle wafer. The stamp is then relaxed via cooling to room temperatureor gradual release of the mechanically induced strain. Release of thisstrain causes the elastomer to return to its initial shape, which inturn forces the device islands of the array to draw closer. Inembodiments, the interconnects are forced to buckle, enabling stretchingand bending characteristics. In embodiments, the area upon which thearray is meant to adhere is pre-treated with a photo-curable adhesive.Alternatively, a layer of PDMS may be used to enhance adhesion.

FIG. 34B details an embodiment of the process for transferring circuitryto the endoscopy device. The transfer is achieved by stamping the planararray of device islands and interconnects onto a curvilinear surfacesuch as an endoscopic device 1680E. 1602A shows the endoscopy devicehaving a thin PDMS shell or adhesive outer layer 250E. 1602B shows thecircuitry 1000E on a carrier substrate 201E. 1602C shows the step ofrotating the endoscopic device 1680E around a single revolution over thesubstrate 201E containing planar array of device islands, the array ofphotodetectors and interconnects will preferentially adhere to thesurface of the endoscopy device 1680E in a curvilinear manner as shownin Step 1602D.

In another embodiment, micro-lens arrays may be required for optimalfocusing and image quality. However, with proper illumination andnegligible distance between the optical array and the surface beingimaged, this requirement may be nullified. In the case where micro-lensarrays are required, they may be created directly as the encapsulatinglayer of the photodetector arrays during stretchable processing. Theymay also be stamped on after the endoscopic devices are made. Thisoptical array is then encapsulated and electronically integrated withthe rest of the endoscopic device in the following manner: electronicdevices which have been processed for stretching, can be picked up witha planar pre-strained PDMS stamp. The pre-strained PDMS stamp is thenrelaxed and brought into contact with the acceptor substrate fortransfer printing. This acceptor surface may be the surface of theendoscopy device, said surface coated with a thin PDMS layer, or aseparate thin appropriately shaped PDMS layer that may later be wrappedaround the endoscope. In the case where the devices are facing outwardson the endoscopy device substrate, they may be encapsulated (while intheir compressed state) with another layer of PDMS, or a liquid layer ofPDMS followed by an upper layer of solid PDMS to make a fluidencapsulation. Other materials/methods may also be applied. In the casewhere the devices are facing outwards on the endoscopy device substrate,they may be electrically externally interfaced at conductive pads thatshould be designed to be located at a convenient location. Anisotropicconductive film (ACF) connectors can be used to interface to theseconductive pads, by pressing and heating the film onto the pads.

In the case where the devices are fully encapsulated or facing inwards,they may be electrically externally interfaced by first removing part ofthe encapsulating polymer over the conductive pads through wet or drychemical etching, or physical mechanical removal of material, includingbut not limited to drilling. At this point, the ACF may be incorporated.Alternatively, the stretchable electronics may be electricallyinterfaced to an ACF prior to the transfer or encapsulation process.

In embodiments, circuitry 1000E may include a flexible LED array on theouter surface of the endoscopy device 1680E, as shown in FIG. 35. Suchan array provides illumination required for optical image capture. Arepresentative process for creating a flexible LED system is as follows:

LEDs are made from quantum well (QW) structures on a GaAs substrate. Inbetween the GaAs substrate and the QW structure is an AlAs sacrificiallayer. The QW structure is etched with reactive ion etching (RIE) todown to the sacrificial layer to form isolated square islands which maybe in the range of, for example, 10-1000 μm on an edge. A partialrelease/undercut of the islands with HF etching is performed.Photoresist is spun onto the substrate and patterned to form squaresaround the corners of the islands, to serve as anchors. A full HFrelease etch is performed to free the islands from the GaAs bulksubstrate; the photoresist anchors prevent the islands from floatingaway during etch, rinse and dry steps. An elastomeric stamp (for examplePDMS) is used to pick up the islands and transfer them to anothersubstrate. The transfer may be done in multiple steps, picking up afraction of the GaAs islands at a time, to rearrange them geometrically.The substrate onto which the islands are transferred for furtherprocessing may be a layer of PET (polyethylene plastic) on a glasssubstrate that can be later peeled off, or a layer of polyimide on topof a PMMA (polymethylmethacrylate) sacrificial layer, or a layer of PDMSetc. Parts of the LED islands are then patterned and wet etched so thatthe bottom n-type contact is exposed; this may be done with, forexample, a H3PO4+H2O2 combination. Parts of the islands are unetched sothat the upper p-type material can be contacted electrically as well.Next, a planarization layer of polyimide is spun on, patterned so thatvias extend down to the p and n type contact regions of the device. Thinfilm wires are deposited and patterned such that the wires to the p-typeregions run in one direction, and the wires to the n-type regions run inan orthogonal direction. One of the other wires should have a gap so asnot to cross-circuit. This gap is bridged by spinning anotherplanarization layer thereover and patterning it with vias to each sideof the gap, and metal is patterned over the planarization layer to makethe connection. Another passivation layer is spun on top, and the entirestack is etched so that the bridges and islands remain encapsulated withpolymer but the intervening areas are completely etched away. Thisallows the bridges to be flexible. The PMMA sacrificial layer isundercut, or the PET layer is peeled off, and the entire sheet withcircuits may be picked up again by PDMS stamp, and flipped over. Thebackside of the lower polyimide, or bottom of the circuits, is coatedwith Cr/SiO2; coating of the bridges is avoided by using a shadow maskevaporation procedure. The samples are subjected to a UV ozone treatmentto impart dangling bonds to the SiO2, facilitating formation of covalentbonds with the next substrate to which the circuits are transferred.This final substrate may be thermally or mechanically pre-strained PDMS,such that after transfer, the strain is relaxed and the devices movecloser together and the bridges pop up and buckle to accommodate thestrain.

The stretchable LED array is transferred to the endoscopy device in amanner similar to that of the cylindrical optical sensor array. It isthen encapsulated and integrated at the device level according to themethods described herein in connection with the micro-lens array. FIG.35 shows an endoscopy device 1680E wherein circuitry 1000E comprises andarray of photodetector and array of LED's (individually shown as 1030E.The LED array may utilize processing 1200E in the form of a logic deviceso that it only illuminates areas of interest during the operation andcan be turned off when not in use as a power-saving mechanism. Devicealso includes a data transmission facility which includes RF antenna1502 to wireless communicate with external devices.

In another embodiment of the present invention, the endoscopy device isequipped with an array of sensors which can be selected from thoseherein including those in connection with the discussion of 1100. Saidsensors working in conjunction with circuitry 1000E to monitor pH, thepresence of chemicals, and/or enzyme activity. IN embodiments, the datacollected by this sensor array is processed by local computing devicesand transmitted via RF antenna or wired telemetry to an externalreceiver for further analysis.

At least some of the sensors in the array may comprise an ion-sensitivefield effect transistor (ISLET), which generate data relating to changesin ion concentration. The output signals are typically a voltage and/orcurrent difference, the magnitude of which varies with the change ofsensed ion (eg. hydronium) and/or enzyme. Other types of chemicalsensors may be also or alternatively be utilized.

Another embodiment of the present invention relates to a capsuleendoscopy device with a plurality of electronic components conformallyfitted to the inside and/or outside walls of the capsule shell in orderto conserve space. Conformal components are created by first performingstretchable processing on suitable materials as described herein. Thebasic components of such an endoscopy device include a passive or activematrix focal plane array, lens, illuminating LEDs, battery and telemetrydevices (antenna and a radio transmitter). Optional components mayinclude sensors described herein including ultrasound transducers,pressure sensors (eg. silicon-based devices utilizing piezo-resistive orcapacitive sensing mechanism, polymer-based sensors, and/or opticallybased sensors that measure physical deflections), temperature sensors(eg. silicon band-gap temperature sensors, Pt resistance temperaturedevices), Ph/enzymatic/chemical sensors (eg. Islets, as discussedabove), targeted drug delivery components, electrocautery devices,biopsy devices, lasers, and heating devices. Components that benefitfrom contact with the GI wall and fluids (eg. chemical sensors, LED,optical arrays) are situated in such a manner as to communicate fluidlyor optically with the outer environment. This may be accomplished, forexample, by placing the devices conformally on the outer surface of thecapsule or through the use of electrodes which relay information fromthe outer region to the inside of the capsule. The remaining components(e.g. battery, telemetry devices) are preferably located on the insideof the capsule.

Methods for creating stretchable focal plane arrays and incorporatingthem into a desired substrate are described above. The same methods usedto process and transfer focal plane arrays (stretchable processing) maybe employed for various single-crystal silicon based electronic devices(e.g. antenna, RF transmitter, ISFET), with circuits being laid out (eg.using CAD tools) in a manner that accommodates mechanical deformationand stretching.

In embodiments where it is desired to incorporate heterogeneousintegrated circuits (non-silicon based devices), a slightly differentapproach may be employed. When creating a device that requiresheterogeneous integration (e.g. LEDs), circuits are typically created ondifferent substrates. After stretchable processing, the electronicdevices are combined onto the same substrate using stamping methodspreviously described. This substrate may be the final destination of thedevices (product integration) or may instead be intermediate (i.e. Arigid, flexible or stretchable material which will be incorporated intothe product at a later time). At this point interconnects may berequired to keep all of the heterogeneous components in electricalcommunication. These may be provided using soft lithography or anotherlow-impact, low-temperature-processing (<400° C.) method with accuratealignment (<5 μm). The integrated circuit is then appropriatelyencapsulated and system/device interconnect integration can be executedas described above in connection with the micro-lens array.

As mentioned above, materials for the substrate used in the embodimentsherein may be biocompatible. Such is the case with substrates includingouter coatings of endoscopy device. In addition to biocompatibility, anypart of the device housing that comes between the imager array and theobject being monitored is preferably transparent. Further, the materialin the outer shell of the endoscopy device facilitates easy travelthrough the GI tract. Examples of suitable biocompatible materials aregiven above.

It is to be understood that the housing of the device described abovemay also be the substrate and vice verse. Therefore, the skilled artisanwill appreciate that certain discussions related to the substrate'smaterial may—in certain embodiments—be understood as to apply to saidhousing.

Referring to FIG. 26, in embodiments the present invention may providefor an imaging array structure, comprising a stretchable non-planarelectronic imaging structure 2602, where the structure includessemiconductor imaging cells 2604 electrically interconnected withstretchable interconnections 2608. The semiconductor may be asingle-crystalline semiconductor. The semiconductor may be a non-singlecrystal silicon material used for photo-detection, such as an amorphoussilicon material, polycrystalline silicon material, single-crystalsilicon material, conductive oxide material, organic material, carbonnano-tube material, and the like. The semiconductor imaging cells mayinclude at least one imaging pixel and support electronics forcontrolling and reading out the image from the at least one imagingpixel. Light may impinge the front-side of the imaging cells as providedin the non-planar electronic imaging structure. Light may impinge theback-side of the imaging cells as provided in the non-planar electronicimaging structure, where the imaging cells have at least one of colorfilters and micro-lenses transfer printed onto the backside of theimaging cells. The imaging structure may be actuated, such as to changethe curvature of the imaging structure. A curved imaging system imagerpackaging may be provided, such as a chip scale packaging, a ball gridarray, and the like. The fabrication of the imaging cells may be on atleast one of a silicon-on-insulator (SOI) and a rigid stack, where thefabrication structure may be a layered order of Silicon, then PolymethylMethacrylate (PMMA), then polyimide (PI), then Silicon. The imagingcells include color filters, such as to provide for color imagecapabilities. The imaging cells may include micro-lenses, such as toprovide for enhanced image quality. The imaging cells may be arranged assensor islands, such as comprised of one pixel per sensor island, ormore than one pixel per sensor island. The imaging array may be shapedin symmetrical non-planar geometry, such as a paraboloid of revolution,a hemisphere, an ellipsoid, and the like. The imaging array structuremay be used to create a camera module, such as including a lens barrelwith at least one lens on a moveable mount, and a circuit for imageprocessing and transmission. The camera module may include a lens, suchas a plastic molded lens. The lens shape may be changed via theapplication of a force, such as a radial tension force, a radialcompression force, and the like. The imaging array may be actuated, suchas to change the curvature of the imaging structure.

Referring to FIG. 27, in embodiments the present invention may providefor an imaging array fabrication process 2702 method, comprisingfabricating an array of semiconductor imaging islands 2704 from asingle-crystal semiconductor substrate, and interconnecting the imagingislands with stretchable interconnections 2708. The semiconductorimaging islands may include at least one imaging pixel and supportelectronics for controlling and reading out the image from the at leastone imaging pixel. The semiconductor may be a single-crystallinesemiconductor. The semiconductor may be a non-single crystal siliconmaterial used for photo-detection, such as an amorphous siliconmaterial, polycrystalline silicon material, single-crystal siliconmaterial, conductive oxide material, organic material, carbon nano-tubematerial, and the like. The semiconductor imaging cells may include atleast one imaging pixel and support electronics for controlling andreading out the image from the at least one imaging pixel. Light mayimpinge the front-side of the imaging cells as provided in thenon-planar electronic imaging structure. Light may impinge the back-sideof the imaging cells as provided in the non-planar electronic imagingstructure, where the imaging cells have at least one of color filtersand micro-lenses transfer printed onto the backside of the imagingcells. The imaging structure may be actuated, such as to change thecurvature of the imaging structure. A curved imaging system imagerpackaging may be provided, such as a chip scale packaging, a ball gridarray, and the like. The fabrication of the imaging cells may be on atleast one of a silicon-on-insulator (SOI) and a rigid stack, where thefabrication structure may be a layered order of Silicon, then PolymethylMethacrylate (PMMA), then polyimide (PI), then Silicon. The imagingcells include color filters, such as to provide for color imagecapabilities. The imaging cells may include micro-lenses, such as toprovide for enhanced image quality. The imaging cells may be arranged assensor islands, such as comprised of one pixel per sensor island, ormore than one pixel per sensor island. The imaging array may be shapedin symmetrical non-planar geometry, such as a paraboloid of revolution,a hemisphere, an ellipsoid, and the like. The imaging array structuremay be used to create a camera module, such as including a lens barrelwith at least one lens on a moveable mount, and a circuit for imageprocessing and transmission. The camera module may include a lens, suchas a plastic molded lens. The lens shape may be changed via theapplication of a force, such as a radial tension force, a radialcompression force, and the like. The imaging array may be actuated, suchas to change the curvature of the imaging structure.

Referring to FIG. 28, in embodiments the present invention may providefor an imaging array facility, comprising a stretchable non-planarelectronic imaging array 2802, where the array may be made up of aplurality of single pixel semiconductor imaging elements 2808electrically interconnected with stretchable interconnections 2810 andmounted on an elastomeric substrate 2804. Each of the single pixelsemiconductor imaging elements may include support electronics. Thesemiconductor may be a single-crystalline semiconductor. Thesemiconductor may be a non-single crystal silicon material used forphoto-detection, such as an amorphous silicon material, polycrystallinesilicon material, single-crystal silicon material, conductive oxidematerial, organic material, carbon nano-tube material, and the like. Thesemiconductor imaging cells may include at least one imaging pixel andsupport electronics for controlling and reading out the image from theat least one imaging pixel. Light may impinge the front-side of theimaging cells as provided in the non-planar electronic imagingstructure. Light may impinge the back-side of the imaging cells asprovided in the non-planar electronic imaging structure, where theimaging cells have at least one of color filters and micro-lensestransfer printed onto the backside of the imaging cells. The imagingstructure may be actuated, such as to change the curvature of theimaging structure. A curved imaging system imager packaging may beprovided, such as a chip scale packaging, a ball grid array, and thelike. The fabrication of the imaging cells may be on at least one of asilicon-on-insulator (SOI) and a rigid stack, where the fabricationstructure may be a layered order of Silicon, then PolymethylMethacrylate (PMMA), then polyimide (PI), then Silicon. The imagingcells include color filters, such as to provide for color imagecapabilities. The imaging cells may include micro-lenses, such as toprovide for enhanced image quality. The imaging cells may be arranged assensor islands, such as comprised of one pixel per sensor island, ormore than one pixel per sensor island. The imaging array may be shapedin symmetrical non-planar geometry, such as a paraboloid of revolution,a hemisphere, an ellipsoid, and the like. The imaging array structuremay be used to create a camera module, such as including a lens barrelwith at least one lens on a moveable mount, and a circuit for imageprocessing and transmission. The camera module may include a lens, suchas a plastic molded lens. The lens shape may be changed via theapplication of a force, such as a radial tension force, a radialcompression force, and the like. The imaging array may be actuated, suchas to change the curvature of the imaging structure.

Referring to FIG. 29, in embodiments the present invention may providefor an imaging array facility, comprising a stretchable non-planarelectronic imaging array 2902, where the array may be made up of aplurality of multiple pixel semiconductor imaging elements 2908, andwhere the imaging elements may be electrically interconnected withstretchable interconnections 2910 and mounted on an elastomericsubstrate 2904. Each of the multiple pixel semiconductor imagingelements may include support electronics. The semiconductor may be asingle-crystalline semiconductor. The semiconductor may be a non-singlecrystal silicon material used for photo-detection, such as an amorphoussilicon material, polycrystalline silicon material, single-crystalsilicon material, conductive oxide material, organic material, carbonnano-tube material, and the like. The semiconductor imaging cells mayinclude at least one imaging pixel and support electronics forcontrolling and reading out the image from the at least one imagingpixel. Light may impinge the front-side of the imaging cells as providedin the non-planar electronic imaging structure. Light may impinge theback-side of the imaging cells as provided in the non-planar electronicimaging structure, where the imaging cells have at least one of colorfilters and micro-lenses transfer printed onto the backside of theimaging cells. The imaging structure may be actuated, such as to changethe curvature of the imaging structure. A curved imaging system imagerpackaging may be provided, such as a chip scale packaging, a ball gridarray, and the like. The fabrication of the imaging cells may be on atleast one of a silicon-on-insulator (SOI) and a rigid stack, where thefabrication structure may be a layered order of Silicon, then PolymethylMethacrylate (PMMA), then polyimide (PI), then Silicon. The imagingcells include color filters, such as to provide for color imagecapabilities. The imaging cells may include micro-lenses, such as toprovide for enhanced image quality. The imaging cells may be arranged assensor islands, such as comprised of one pixel per sensor island, ormore than one pixel per sensor island. The imaging array may be shapedin symmetrical non-planar geometry, such as a paraboloid of revolution,a hemisphere, an ellipsoid, and the like. The imaging array structuremay be used to create a camera module, such as including a lens barrelwith at least one lens on a moveable mount, and a circuit for imageprocessing and transmission. The camera module may include a lens, suchas a plastic molded lens. The lens shape may be changed via theapplication of a force, such as a radial tension force, a radialcompression force, and the like.

Referring to FIG. 30, in embodiments the present invention may providefor an imaging device replacement method 3002, comprising a stretchablenon-planar electronic imaging device 3004, where the structure mayinclude semiconductor imaging cells 3008 electrically interconnectedwith stretchable interconnections 3010, and replacing a planarelectronic imaging device 3014 in an imaging facility 3012 to improvethe imaging performance of the imaging facility. The replacement may bean integrated replacement with the imaging facility, an imaging sensorwithin the imaging facility, and the like. The semiconductor may be asingle-crystalline semiconductor. The semiconductor may be a non-singlecrystal silicon material used for photo-detection, such as an amorphoussilicon material, polycrystalline silicon material, single-crystalsilicon material, conductive oxide material, organic material, carbonnano-tube material, and the like. The semiconductor imaging cells mayinclude at least one imaging pixel and support electronics forcontrolling and reading out the image from the at least one imagingpixel. Light may impinge the front-side of the imaging cells as providedin the non-planar electronic imaging structure. Light may impinge theback-side of the imaging cells as provided in the non-planar electronicimaging structure, where the imaging cells have at least one of colorfilters and micro-lenses transfer printed onto the backside of theimaging cells. The imaging structure may be actuated, such as to changethe curvature of the imaging structure. A curved imaging system imagerpackaging may be provided, such as a chip scale packaging, a ball gridarray, and the like. The fabrication of the imaging cells may be on atleast one of a silicon-on-insulator (SOI) and a rigid stack, where thefabrication structure may be a layered order of Silicon, then PolymethylMethacrylate (PMMA), then polyimide (PI), then Silicon. The imagingcells include color filters, such as to provide for color imagecapabilities. The imaging cells may include micro-lenses, such as toprovide for enhanced image quality. The imaging cells may be arranged assensor islands, such as comprised of one pixel per sensor island, ormore than one pixel per sensor island. The imaging array may be shapedin symmetrical non-planar geometry, such as a paraboloid of revolution,a hemisphere, an ellipsoid, and the like. The imaging array structuremay be used to create a camera module, such as including a lens barrelwith at least one lens on a moveable mount, and a circuit for imageprocessing and transmission. The camera module may include a lens, suchas a plastic molded lens. The lens shape may be changed via theapplication of a force, such as a radial tension force, a radialcompression force, and the like. The imaging array may be actuated, suchas to change the curvature of the imaging structure.

Referring to FIG. 31, in embodiments the present invention may providefor an imaging facility, comprising a stretchable non-planar electronicimaging structure 3102, where the structure may include semiconductorimaging cells 3104 electrically interconnected with stretchableinterconnections 3108, and at least one mechanical actuation device 3112attached to the imaging structure, where the actuation device may becapable of changing the shape of an imaging surface 3110 of the imagingstructure. The semiconductor may be a single-crystalline semiconductor.The semiconductor may be a non-single crystal silicon material used forphoto-detection, such as an amorphous silicon material, polycrystallinesilicon material, single-crystal silicon material, conductive oxidematerial, organic material, carbon nano-tube material, and the like. Thesemiconductor imaging cells may include at least one imaging pixel andsupport electronics for controlling and reading out the image from theat least one imaging pixel. Light may impinge the front-side of theimaging cells as provided in the non-planar electronic imagingstructure. Light may impinge the back-side of the imaging cells asprovided in the non-planar electronic imaging structure, where theimaging cells have at least one of color filters and micro-lensestransfer printed onto the backside of the imaging cells. The imagingstructure may be actuated, such as to change the curvature of theimaging structure. A curved imaging system imager packaging may beprovided, such as a chip scale packaging, a ball grid array, and thelike. The fabrication of the imaging cells may be on at least one of asilicon-on-insulator (SOI) and a rigid stack, where the fabricationstructure may be a layered order of Silicon, then PolymethylMethacrylate (PMMA), then polyimide (PI), then Silicon. The imagingcells include color filters, such as to provide for color imagecapabilities. The imaging cells may include micro-lenses, such as toprovide for enhanced image quality. The imaging cells may be arranged assensor islands, such as comprised of one pixel per sensor island, ormore than one pixel per sensor island. The imaging array may be shapedin symmetrical non-planar geometry, such as a paraboloid of revolution,a hemisphere, an ellipsoid, and the like. The imaging array structuremay be used to create a camera module, such as including a lens barrelwith at least one lens on a moveable mount, and a circuit for imageprocessing and transmission. The camera module may include a lens, suchas a plastic molded lens. The lens shape may be changed via theapplication of a force, such as a radial tension force, a radialcompression force, and the like. The imaging array may be actuated, suchas to change the curvature of the imaging structure.

Referring to FIG. 32, in embodiments the present invention may providefor an imaging array fabrication process 3202 method, comprisingfabricating an array of semiconductor imaging elements 3204,interconnecting the elements with stretchable interconnections 3208, andtransfer printing 3210 the array with a pre-strained elastomeric stamp3212 to a secondary non-planar surface 3214. The semiconductor may be asingle-crystalline semiconductor. The semiconductor may be a non-singlecrystal silicon material used for photo-detection, such as an amorphoussilicon material, polycrystalline silicon material, single-crystalsilicon material, conductive oxide material, organic material, carbonnano-tube material, and the like. The semiconductor imaging cells mayinclude at least one imaging pixel and support electronics forcontrolling and reading out the image from the at least one imagingpixel. Light may impinge the front-side of the imaging cells as providedin the non-planar electronic imaging structure. Light may impinge theback-side of the imaging cells as provided in the non-planar electronicimaging structure, where the imaging cells have at least one of colorfilters and micro-lenses transfer printed onto the backside of theimaging cells. The imaging structure may be actuated, such as to changethe curvature of the imaging structure. A curved imaging system imagerpackaging may be provided, such as a chip scale packaging, a ball gridarray, and the like. The fabrication of the imaging cells may be on atleast one of a silicon-on-insulator (SOI) and a rigid stack, where thefabrication structure may be a layered order of Silicon, then PolymethylMethacrylate (PMMA), then polyimide (PI), then Silicon. The imagingcells include color filters, such as to provide for color imagecapabilities. The imaging cells may include micro-lenses, such as toprovide for enhanced image quality. The imaging cells may be arranged assensor islands, such as comprised of one pixel per sensor island, ormore than one pixel per sensor island. The imaging array may be shapedin symmetrical non-planar geometry, such as a paraboloid of revolution,a hemisphere, an ellipsoid, and the like. The imaging array structuremay be used to create a camera module, such as including a lens barrelwith at least one lens on a moveable mount, and a circuit for imageprocessing and transmission. The camera module may include a lens, suchas a plastic molded lens. The lens shape may be changed via theapplication of a force, such as a radial tension force, a radialcompression force, and the like. The imaging array may be actuated, suchas to change the curvature of the imaging structure.

Referring to FIG. 33, in embodiments the present invention may providefor an imaging array fabrication process 3302 method, comprisingfabricating an imaging array of semiconductor back side illuminationimaging elements 3304, where the fabrication of the imaging array mayincludes etching and transfer printing 3308 steps: (1) a first step 3310fabricating the imaging array on a first semiconductor substrate, wherethe imaging array structure is separated from the first semiconductorsubstrate by an oxide layer, (2) a second step 3312 etching outerportions of the oxide layer, (3) a third step 3314 separating andlifting the imaging array off from the first semiconductor substrateutilizing transfer printing with a first elastomeric stamp on a frontside of the imaging array, (4) a forth step 3318 transferring theimaging array to a second elastomeric stamp which contacts a back sideof the imaging array; and (5) a fifth step 3320 transferring the imagingarray to a second semiconductor substrate, where the back side of theimaging array is now exposed for illumination. In embodiments, a lensmay be attached to at least one of the back side illumination imagingelements, such as a micro-lens. A filter may be attached to at least oneof the back side illumination imaging elements, such as a color filter.The semiconductor may be a single-crystalline semiconductor. Thesemiconductor may be a non-single crystal silicon material used forphoto-detection, such as an amorphous silicon material, polycrystallinesilicon material, single-crystal silicon material, conductive oxidematerial, organic material, carbon nano-tube material, and the like. Thesemiconductor imaging cells may include at least one imaging pixel andsupport electronics for controlling and reading out the image from theat least one imaging pixel. Light may impinge the front-side of theimaging cells as provided in the non-planar electronic imagingstructure. Light may impinge the back-side of the imaging cells asprovided in the non-planar electronic imaging structure, where theimaging cells have at least one of color filters and micro-lensestransfer printed onto the backside of the imaging cells. The imagingstructure may be actuated, such as to change the curvature of theimaging structure. A curved imaging system imager packaging may beprovided, such as a chip scale packaging, a ball grid array, and thelike. The fabrication of the imaging cells may be on at least one of asilicon-on-insulator (SOI) and a rigid stack, where the fabricationstructure may be a layered order of Silicon, then PolymethylMethacrylate (PMMA), then polyimide (PI), then Silicon. The imagingcells include color filters, such as to provide for color imagecapabilities. The imaging cells may include micro-lenses, such as toprovide for enhanced image quality. The imaging cells may be arranged assensor islands, such as comprised of one pixel per sensor island, ormore than one pixel per sensor island. The imaging array may be shapedin symmetrical non-planar geometry, such as a paraboloid of revolution,a hemisphere, an ellipsoid, and the like. The imaging array structuremay be used to create a camera module, such as including a lens barrelwith at least one lens on a moveable mount, and a circuit for imageprocessing and transmission. The camera module may include a lens, suchas a plastic molded lens. The lens shape may be changed via theapplication of a force, such as a radial tension force, a radialcompression force, and the like. The imaging array may be actuated, suchas to change the curvature of the imaging structure.

Certain of the methods and systems described in connection with theinvention described (hereinafter referred to as the “Subject Methods andSystems”) may be deployed in part or in whole through a machine thatexecutes computer software, program codes, and/or instructions on aprocessor integrated with or separate from the electronic circuitrydescribed herein. Said certain methods and systems will be apparent tothose skilled in the art, and nothing below is meant to limit that whichhas already been disclosed but rather to supplement it.

The active stretchable or flexible circuitry described herein may beconsidered the machine necessary to deploy the Subject Methods andSystem in full or in part, or a separately located machine may deploythe Subject Methods and Systems in whole or in part. Thus, “machine” asreferred to herein may be applied to the circuitry described above, aseparate processor, separate interface electronics or combinationsthereof.

The Subject Methods and Systems invention may be implemented as a methodon the machine, as a system or apparatus as part of or in relation tothe machine, or as a computer program product embodied in a computerreadable medium executing on one or more of the machines. Inembodiments, the processor may be part of a server, client, networkinfrastructure, mobile computing platform, stationary computingplatform, or other computing platform. A processor may be any kind ofcomputational or processing device capable of executing programinstructions, codes, binary instructions and the like. The processor maybe or include a signal processor, digital processor, embedded processor,microprocessor or any variant such as a co-processor (math co-processor,graphic co-processor, communication co-processor and the like) and thelike that may directly or indirectly facilitate execution of programcode or program instructions stored thereon. In addition, the processormay enable execution of multiple programs, threads, and codes. Thethreads may be executed simultaneously to enhance the performance of theprocessor and to facilitate simultaneous operations of the application.By way of implementation, methods, program codes, program instructionsand the like described herein may be implemented in one or more thread.The thread may spawn other threads that may have assigned prioritiesassociated with them; the processor may execute these threads based onpriority or any other order based on instructions provided in theprogram code. The processor, or any machine utilizing one, may includememory that stores methods, codes, instructions and programs asdescribed herein and elsewhere. The processor may access a storagemedium through an interface that may store methods, codes, andinstructions as described herein and elsewhere. The storage mediumassociated with the processor for storing methods, programs, codes,program instructions or other type of instructions capable of beingexecuted by the computing or processing device may include but may notbe limited to one or more of a CD-ROM, DVD, memory, hard disk, flashdrive, RAM, ROM, cache and the like. Nothing in this paragraph or theparagraphs below is meant to limit or contradict the description of theprocessing facility described herein and throughout.

A processor may include one or more cores that may enhance speed andperformance of a multiprocessor. In embodiments, the process may be adual core processor, quad core processors, other chip-levelmultiprocessor and the like that combine two or more independent cores(called a die).

The Subject Methods and Systems described herein may be deployed in partor in whole through a machine that executes computer software on aserver, client, firewall, gateway, hub, router, or other such computerand/or networking hardware. The software program may be associated witha server that may include a file server, print server, domain server,internet server, intranet server and other variants such as secondaryserver, host server, distributed server and the like. The server mayinclude one or more of memories, processors, computer readable media,storage media, ports (physical and virtual), communication devices, andinterfaces capable of accessing other servers, clients, machines, anddevices through a wired or a wireless medium, and the like. The methods,programs or codes as described herein and elsewhere may be executed bythe server. In addition, other devices required for execution of methodsas described in this application may be considered as a part of theinfrastructure associated with the server.

The server may provide an interface to other devices including, withoutlimitation, clients, other servers, printers, database servers, printservers, file servers, communication servers, distributed servers andthe like. Additionally, this coupling and/or connection may facilitateremote execution of program across the network. The networking of someor all of these devices may facilitate parallel processing of a programor method at one or more location without deviating from the scope ofthe invention. In addition, any of the devices attached to the serverthrough an interface may include at least one storage medium capable ofstoring methods, programs, code and/or instructions. A centralrepository may provide program instructions to be executed on differentdevices. In this implementation, the remote repository may act as astorage medium for program code, instructions, and programs.

If the Subject Methods and Systems are embodied in a software program,the software program may be associated with a client that may include afile client, print client, domain client, internet client, intranetclient and other variants such as secondary client, host client,distributed client and the like. The client may include one or more ofmemories, processors, computer readable media, storage media, ports(physical and virtual), communication devices, and interfaces capable ofaccessing other clients, servers, machines, and devices through a wiredor a wireless medium, and the like. The methods, programs or codes asdescribed herein and elsewhere may be executed by the client. Inaddition, other devices required for execution of methods as describedin this application may be considered as a part of the infrastructureassociated with the client.

The client may provide an interface to other devices including, withoutlimitation, servers, other clients, printers, database servers, printservers, file servers, communication servers, distributed servers andthe like. Additionally, this coupling and/or connection may facilitateremote execution of program across the network. The networking of someor all of these devices may facilitate parallel processing of a programor method at one or more location without deviating from the scope ofthe invention. In addition, any of the devices attached to the clientthrough an interface may include at least one storage medium capable ofstoring methods, programs, applications, code and/or instructions. Acentral repository may provide program instructions to be executed ondifferent devices. In this implementation, the remote repository may actas a storage medium for program code, instructions, and programs.

The Subject Methods and Systems described herein may be deployed in partor in whole through network infrastructures. The network infrastructuremay include elements such as computing devices, servers, routers, hubs,firewalls, clients, personal computers, communication devices, routingdevices and other active and passive devices, modules and/or componentsas known in the art. The computing and/or non-computing device(s)associated with the network infrastructure may include, apart from othercomponents, a storage medium such as flash memory, buffer, stack, RAM,ROM and the like. The processes, methods, program codes, instructionsdescribed herein and elsewhere may be executed by one or more of thenetwork infrastructural elements.

The methods, program codes, and instructions pertaining to the SubjectMethods and Systems described herein and elsewhere may be implemented ona cellular network having multiple cells. The cellular network mayeither be frequency division multiple access (FDMA) network or codedivision multiple access (CDMA) network. The cellular network mayinclude mobile devices, cell sites, base stations, repeaters, antennas,towers, and the like. The cell network may be a GSM, GPRS, 3G, EVDO,mesh, or other networks types.

The methods, program codes, and instructions pertaining to the SubjectMethods and Systems described herein and elsewhere may be implemented onor through mobile devices. The mobile devices may include navigationdevices, cell phones, mobile phones, mobile personal digital assistants,laptops, palmtops, netbooks, pagers, electronic books readers, musicplayers and the like. These devices may include, apart from othercomponents, a storage medium such as a flash memory, buffer, RAM, ROMand one or more computing devices. The computing devices associated withmobile devices may be enabled to execute program codes, methods, andinstructions stored thereon. Alternatively, the mobile devices may beconfigured to execute instructions in collaboration with other devices.The mobile devices may communicate with base stations interfaced withservers and configured to execute program codes. The mobile devices maycommunicate on a peer to peer network, mesh network, or othercommunications network. The program code may be stored on the storagemedium associated with the server and executed by a computing deviceembedded within the server. The base station may include a computingdevice and a storage medium. The storage device may store program codesand instructions executed by the computing devices associated with thebase station.

The computer software, program codes, and/or instructions pertaining tothe Subject Methods and Systems may be stored and/or accessed on machinereadable media that may include: computer components, devices, andrecording media that retain digital data used for computing for someinterval of time; semiconductor storage known as random access memory(RAM); mass storage typically for more permanent storage, such asoptical discs, forms of magnetic storage like hard disks, tapes, drums,cards and other types; processor registers, cache memory, volatilememory, non-volatile memory; optical storage such as CD, DVD; removablemedia such as flash memory (e.g. USB sticks or keys), floppy disks,magnetic tape, paper tape, punch cards, standalone RAM disks, Zipdrives, removable mass storage, off-line, and the like; other computermemory such as dynamic memory, static memory, read/write storage,mutable storage, read only, random access, sequential access, locationaddressable, file addressable, content addressable, network attachedstorage, storage area network, bar codes, magnetic ink, and the like.

The Subject Methods and Systems described herein may transform physicaland/or or intangible items from one state to another. The methods andsystems described herein may also transform data representing physicaland/or intangible items from one state to another.

The elements described and depicted herein and the functions thereof maybe implemented on machines through computer executable media having aprocessor capable of executing program instructions stored thereon as amonolithic software structure, as standalone software modules, or asmodules that employ external routines, code, services, and so forth, orany combination of these, and all such implementations may be within thescope of the present disclosure. Examples of such machines may include,but may not be limited to, personal digital assistants, laptops,personal computers, mobile phones, other handheld computing devices,medical equipment, wired or wireless communication devices, transducers,chips, calculators, satellites, tablet PCs, electronic books, gadgets,electronic devices, devices having artificial intelligence, computingdevices, networking equipments, servers, routers and the like.Furthermore, the elements depicted in the flow chart and block diagramsor any other logical component may be implemented on a machine capableof executing program instructions. Thus, while the foregoingdescriptions set forth functional aspects of the disclosed systems, noparticular arrangement of software for implementing these functionalaspects should be inferred from these descriptions unless explicitlystated or otherwise clear from the context. Similarly, it will beappreciated that the various steps identified and described above may bevaried, and that the order of steps may be adapted to particularapplications of the techniques disclosed herein. All such variations andmodifications are intended to fall within the scope of this disclosure.As such, the depiction and/or description of an order for various stepsshould not be understood to require a particular order of execution forthose steps, unless required by a particular application, or explicitlystated or otherwise clear from the context.

The Subject Methods and Systems, and steps associated therewith, may berealized in hardware, software or any combination of hardware andsoftware suitable for a particular application. The hardware may includea general purpose computer and/or dedicated computing device or specificcomputing device or particular aspect or component of a specificcomputing device. The processes may be realized in one or moremicroprocessors, microcontrollers, embedded microcontrollers,programmable digital signal processors or other programmable device,along with internal and/or external memory. The processes may also, orinstead, be embodied in an application specific integrated circuit, aprogrammable gate array, programmable array logic, or any other deviceor combination of devices that may be configured to process electronicsignals. It will further be appreciated that one or more of theprocesses may be realized as a computer executable code capable of beingexecuted on a machine readable medium.

The computer executable code may be created using a structuredprogramming language such as C, an object oriented programming languagesuch as C++, or any other high-level or low-level programming language(including assembly languages, hardware description languages, anddatabase programming languages and technologies) that may be stored,compiled or interpreted to run on one of the above devices, as well asheterogeneous combinations of processors, processor architectures, orcombinations of different hardware and software, or any other machinecapable of executing program instructions.

Thus, in one aspect, methods described above in connection with theSubject Systems and Methods and combinations thereof may be embodied incomputer executable code that, when executing on one or more computingdevices, performs the steps thereof. In another aspect, the methods maybe embodied in systems that perform the steps thereof, and may bedistributed across devices in a number of ways, or all of thefunctionality may be integrated into a dedicated, standalone device orother hardware. In another aspect, the means for performing the stepsassociated with the processes described above may include any of thehardware and/or software described above. All such permutations andcombinations are intended to fall within the scope of the presentdisclosure.

While the invention has been described in connection with certainpreferred embodiments, other embodiments would be understood by one ofordinary skill in the art and are encompassed herein.

All documents referenced herein are hereby incorporated by reference.

1. An imaging array fabrication process method, comprising: fabricatingan array of semiconductor imaging islands from a single-crystalsemiconductor substrate; interconnecting the imaging islands withstretchable interconnections; and disposing at least one micro-lens overat least a portion of at least one semiconductor imaging island of thearray of one semiconductor imaging islands.
 2. An imaging arrayfabrication process method, comprising: fabricating an array ofsemiconductor imaging elements; interconnecting the elements withstretchable interconnections; disposing at least one micro-lens over atleast a portion of at least one semiconductor imaging element of thearray of one semiconductor imaging elements; and transfer printing thearray with a pre-strained elastomeric stamp to a secondary non-planarsurface.
 3. The method of claim 2, wherein the semiconductor is asingle-crystalline semiconductor.
 4. The method of claim 2, wherein thesemiconductor is a non-single crystal silicon material used forphoto-detection.
 5. The method of claim 4, wherein the material isamorphous silicon material.
 6. The method of claim 4, wherein thematerial is polycrystalline silicon material.
 7. The method of claim 4,wherein the material is single-crystal silicon material.
 8. The methodof claim 4, wherein the material is conductive oxide material.
 9. Themethod of claim 4, wherein the material is organic material.
 10. Themethod of claim 4, wherein the material is carbon nano-tube material.11. The method of claim 2, wherein the semiconductor imaging elementsinclude at least one imaging pixel and support electronics forcontrolling and reading out the image from the at least one imagingpixel.
 12. The method of claim 2, wherein light impinges the front-sideof the semiconductor imaging elements.
 13. The method of claim 2,wherein light impinges the back-side of the semiconductor imagingelements.
 14. The method of claim 13, wherein the semiconductor imagingelements have at least one of color filters and the at least onemicro-lens transfer printed onto the backside of the semiconductorimaging elements.
 15. The method of claim 2, wherein the surface isactuated through an applied force.
 16. The method of claim 15, whereinthe actuated surface changes the curvature of the surface.
 17. Themethod of claim 2, further comprising a curved imaging system imagerpackaging in which the non-planar surface in mounted.
 18. The method ofclaim 17, wherein the packaging is a chip scale packaging.
 19. Themethod of claim 17, wherein the packaging is a ball grid array.
 20. Themethod of claim 2, wherein the of fabricating the array of semiconductorimaging elements is on at least one of a silicon-on-insulator (S01) anda rigid stack.
 21. The method of claim 20, wherein the fabricationstructure is a layered order of Silicon, then Polymethyl Methacrylate(PMMA), then polyimide (PI), and then Silicon.
 22. The method of claim2, wherein the semiconductor imaging elements include color filters. 23.The method of claim 22, wherein the color filters provide for colorimage capabilities.
 24. The method of claim 2, wherein the at least onemicro-lens provides for enhanced image quality.
 25. The method of claim2, wherein the semiconductor imaging elements are arranged as sensorislands.
 26. The method of claim 25, wherein the sensor islands arecomprised of one pixel per sensor island.
 27. The method of claim 25,wherein the sensor islands are comprised of more than one pixel persensor island.
 28. The method of claim 25, wherein the sensor islandsinclude support electronics.
 29. The method of claim 2, wherein theimaging array is shaped in symmetrical nonplanar geometry.
 30. Themethod of claim 29, wherein the geometry is a paraboloid of revolution.31. The method of claim 29, wherein the geometry is a hemisphere. 32.The method of claim 29, wherein the geometry is an ellipsoid.
 33. Themethod of claim 2, wherein the imaging array is used to create a cameramodule.
 34. The method of claim 33, wherein the camera module includes alens barrel with at least one lens on a moveable mount, and a circuitfor image processing and transmission.
 35. The method of claim 33,wherein the camera module includes a lens.
 36. The method of claim 35,wherein the lens is a plastic molded lens.
 37. The method of claim 35,wherein the lens shape is changed via the application of a force. 38.The method of claim 37, wherein the force is a radial tension force. 39.The method of claim 37, wherein the force is a radial compression force.40. The method of claim 2, wherein the imaging array is included in asecurity imager.
 41. The method of claim 2, wherein the imaging array isincluded in an inspection Imager.
 42. The method of claim 2, wherein theimaging array is included in a metrology imager.
 43. The method of claim2, wherein the imaging array is included in a space-based Imager. 44.The method of claim 2, wherein the imaging array is included in a mannedvehicle.
 45. The method of claim 2, wherein the imaging array isincluded in an unmanned vehicle.
 46. The method of claim 2, wherein theimaging array is included in an endoscopic Imager.